PhD requires technology - is this something I will have to fund? I'm applying to do a PhD in Computer Science at a UK university. While I'm up for some funding I've been told it's very competitive so I shouldn't count on it. That's fine, and I'm prepared to self fund. 

However my PhD proposal will require wearable tech, and my supervisor had advised that I think about having a group of 15 or so in the initial test stages. Does anyone have any experience of whether or not I'll have to purchase this myself, or if this is something the university will help cover the cost of? I appreciate it's probably the former, but it's something I need to know prior to starting. 

On top of the PhD costs it could easily be another £3000 or so in order to buy all the tech - so I'll need to work out whether I can afford it!
As a student, you should not be required to fund equipment purchases yourself.  Rather, it is your supervisor's responsibility to work with you to scope a project that is within the funding that they wish to allocate to it.  So if your supervisor wants to do a study with 15 people, your supervisor needs to have a sufficient budget to support it.  Otherwise, you might end up, say, doing your work in simulation instead, which is much cheaper but less convincing in its results.

Now, some students do buy small things themselves, especially if it is a low-cost "toy" that they want to play with themselves (e.g., a Raspberry Pi or a phone sensor pack) and they don't want to go through the delay and hassle of university purchasing.  That's an exception, however, and certainly not to be expected for a multi-user study.