The easiest way would be to create an image of the current SSD and save it on the 1T HDD. You can use Macrium Reflect (free) to create an image of all partitions on the SSD, and select the option to verify it. When that's done, use Macrium to create the bootable USB stick you'll need. Next, swap in the new SSD and close up. When that's done, plug in the Macrium USB stick into PC with power off. Power on and start tapping F12 to open the boot menu. Select the option to boot from USB. When Macrium loads from USB, use it transfer the image saved on the HDD onto the new SSD. Look for options to increase the size of the partitions during (or after) transferring the image onto the new SSD so you can use all its extra space. The new SSD will automatically become the boot drive. Alternatively, you may be able to keep the existing SSD by freeing up space. (These are good to do even if you install a larger SSD.): EDITED
My 3670 came with a 256 gb M2 card as it's only storage and contains the OS and a few other partitions and is the boot drive. I added a 1 TB hard drive later. I want to replace the M2 card with a larger card. Is it just a case of buying a card and USB adapter to clone the original and just swap it out? Crucial shows a few as compatible.
Inspiron 3670 M2 upgrade