Can someone recommend me a decent keyboard? This is my first time buying and I don't really know what I want so I'm looking for an all-around good quality full size keyboard for around £100-150. Thanks for any input!

I would suggest you to check some Yamaha keyboards.
Considering it's your first time, their ''low-mid'' range product will be just fine.

I have a Pse403 and it does the job (I use it to write chords and background music).

i have a yamaha psr-e333. one nice thing about it is it has a usb port for connecting to the computer instead of needing the old type ports. handy if you want to do that sort of thing.