user59649: I've created a bitcoin.service file as found here:
https://github.com/bitcoin/bitcoin/blob/master/contrib/init/bitcoind.service
However i've modified it as i build bitcoin-core from source to the following:
https://gist.github.com/anonymous/7e1bca97739147d698327d7f3a119992
It is installed to:
/lib/systemd/system
As apparently in this version of Ubuntu it must be there
It runs when i run this command:
bitcoind -daemon -pid=/home/chris/.bitcoin/bitcoind.pid -
conf=/home/chris/.bitcoin/bitcoin.conf -datadir=/home/chris/.bitcoin/ 
-disablewallet

However trying to run:
systemctl start bitcoind

Gives this error
bitcoind.service - Bitcoin's distributed currency daemon
   Loaded: loaded (/lib/systemd/system/bitcoind.service; enabled; 
vendor preset: enabled)
   Active: failed (Result: exit-code) since Sun 2017-10-15 17:27:38 
BST; 2s ago
  Process: 4180 ExecStart=/home/chris/.bitcoin/bitcoind -daemon -
pid=/home/chris/.bitcoin/bitcoind.pid -
conf=/home/chris/.bitcoin/bitcoin.conf -datadir=/home/chris/.bitcoin/ 
-disablewallet (code=exited, status=203

Oct 15 17:27:38 chris-GE60-2PL systemd[1]: bitcoind.service: Unit 
entered failed state.
Oct 15 17:27:38 chris-GE60-2PL systemd[1]: bitcoind.service: Failed 
with result 'exit-code'.
Oct 15 17:27:38 chris-GE60-2PL systemd[1]: bitcoind.service: Service 
hold-off time over, scheduling restart.
Oct 15 17:27:38 chris-GE60-2PL systemd[1]: Stopped Bitcoin's 
distributed currency daemon.
Oct 15 17:27:38 chris-GE60-2PL systemd[1]: bitcoind.service: Start 
request repeated too quickly.
Oct 15 17:27:38 chris-GE60-2PL systemd[1]: Failed to start Bitcoin's 
distributed currency daemon.
Oct 15 17:27:38 chris-GE60-2PL systemd[1]: bitcoind.service: Unit 
entered failed state.
Oct 15 17:27:38 chris-GE60-2PL systemd[1]: bitcoind.service: Failed 
with result 'exit-code'.

Does anyone know what i'm doing wrong here ?

user81938: 
It runs when i run this command:
bitcoind -daemon -pid=/home/chris/.bitcoin/bitcoind.pid -
conf=/home/chris/.bitcoin/bitcoin.conf -datadir=/home/chris/.bitcoin/ 
-disablewallet


When you run that command, where are you in your server? At the base level of your home folder? Your service file ExecStart= must point to the same location, and currently it's looking for bitcoind in /home/chris/.bitcoin/. Are you sure bitcoind is inside the directory .bitcoin in your home folder?
As a side note, that is a odd location for the binary. Consider placing bitcoind and bitcoin-cli in /usr/local/bin/. That way you can run it from anywhere in your server without specifying a path. But for the service file, you'd then should specify the full path, such as 
ExecStart=/usr/local/bin/bitcoind -daemon -pid=/home/chris/.bitcoin/bitcoind.pid \
-conf=/home/chris/.bitcoin/bitcoin.conf -datadir=/home/chris/.bitcoin/ -disablewallet

You should also consider changing the location of the PID file and you can also omit -datadir=/home/chris/.bitcoin/, as bitcoind will by default look for the data dir in that location, since the service is being started by the user 'chris'. These are suggestions taken from the official Bitcoin template you linked in your post.
Don't forget to sudo systemctl daemon-reload after you make changes to systemd service files, before sudo systemctl restart <service-name.service> for example.

59649: <p>I've created a bitcoin.service file as found here:</p>

<p><a href="https://github.com/bitcoin/bitcoin/blob/master/contrib/init/bitcoind.service" rel="nofollow noreferrer">https://github.com/bitcoin/bitcoin/blob/master/contrib/init/bitcoind.service</a></p>

<p>However i've modified it as i build bitcoin-core from source to the following:</p>

<p><a href="https://gist.github.com/anonymous/7e1bca97739147d698327d7f3a119992" rel="nofollow noreferrer">https://gist.github.com/anonymous/7e1bca97739147d698327d7f3a119992</a></p>

<p>It is installed to:</p>

<p>/lib/systemd/system</p>

<p>As apparently in this version of Ubuntu it must be there</p>

<p>It runs when i run this command:</p>

<pre><code>bitcoind -daemon -pid=/home/chris/.bitcoin/bitcoind.pid -
conf=/home/chris/.bitcoin/bitcoin.conf -datadir=/home/chris/.bitcoin/ 
-disablewallet
</code></pre>

<p>However trying to run:</p>

<pre><code>systemctl start bitcoind
</code></pre>

<p>Gives this error</p>

<pre><code>bitcoind.service - Bitcoin's distributed currency daemon
   Loaded: loaded (/lib/systemd/system/bitcoind.service; enabled; 
vendor preset: enabled)
   Active: failed (Result: exit-code) since Sun 2017-10-15 17:27:38 
BST; 2s ago
  Process: 4180 ExecStart=/home/chris/.bitcoin/bitcoind -daemon -
pid=/home/chris/.bitcoin/bitcoind.pid -
conf=/home/chris/.bitcoin/bitcoin.conf -datadir=/home/chris/.bitcoin/ 
-disablewallet (code=exited, status=203

Oct 15 17:27:38 chris-GE60-2PL systemd[1]: bitcoind.service: Unit 
entered failed state.
Oct 15 17:27:38 chris-GE60-2PL systemd[1]: bitcoind.service: Failed 
with result 'exit-code'.
Oct 15 17:27:38 chris-GE60-2PL systemd[1]: bitcoind.service: Service 
hold-off time over, scheduling restart.
Oct 15 17:27:38 chris-GE60-2PL systemd[1]: Stopped Bitcoin's 
distributed currency daemon.
Oct 15 17:27:38 chris-GE60-2PL systemd[1]: bitcoind.service: Start 
request repeated too quickly.
Oct 15 17:27:38 chris-GE60-2PL systemd[1]: Failed to start Bitcoin's 
distributed currency daemon.
Oct 15 17:27:38 chris-GE60-2PL systemd[1]: bitcoind.service: Unit 
entered failed state.
Oct 15 17:27:38 chris-GE60-2PL systemd[1]: bitcoind.service: Failed 
with result 'exit-code'.
</code></pre>

<p>Does anyone know what i'm doing wrong here ?</p>
 81938: <blockquote>
  <p>It runs when i run this command:</p>

<pre><code>bitcoind -daemon -pid=/home/chris/.bitcoin/bitcoind.pid -
conf=/home/chris/.bitcoin/bitcoin.conf -datadir=/home/chris/.bitcoin/ 
-disablewallet
</code></pre>
</blockquote>

<p>When you run that command, where are you in your server? At the base level of your home folder? Your service file <code>ExecStart=</code> must point to the same location, and currently it's looking for <code>bitcoind</code> in <code>/home/chris/.bitcoin/</code>. Are you sure <code>bitcoind</code> is inside the directory <code>.bitcoin</code> in your home folder?</p>

<p>As a side note, that is a odd location for the binary. Consider placing <code>bitcoind</code> and <code>bitcoin-cli</code> in <code>/usr/local/bin/</code>. That way you can run it from anywhere in your server without specifying a path. But for the service file, you'd then should specify the full path, such as </p>

<pre><code>ExecStart=/usr/local/bin/bitcoind -daemon -pid=/home/chris/.bitcoin/bitcoind.pid \
-conf=/home/chris/.bitcoin/bitcoin.conf -datadir=/home/chris/.bitcoin/ -disablewallet
</code></pre>

<p>You should also consider changing the location of the PID file and you can also omit <code>-datadir=/home/chris/.bitcoin/</code>, as <code>bitcoind</code> will by default look for the data dir in that location, since the service is being started by the user 'chris'. These are suggestions taken from the official Bitcoin template you linked in your post.</p>

<p>Don't forget to <code>sudo systemctl daemon-reload</code> after you make changes to systemd service files, before <code>sudo systemctl restart &lt;service-name.service&gt;</code> for example.</p>
