A SIM card is a SIM card is a SIM card. i.e. they're not linked to any particular phone model. What you need to think about is which phone provider offers the best deal for the way that you'll be using your phone. I use Asda Mobile, which offers cheap deals:
https://mobile.asda.com/bundles
Go for the £5 per month bundle if you rarely make outgoing calls and you only want to use the internet for a bit of emailing and light web browsing. £7 per month gets you an average of 10 minutes per day call time and the ability to watch quite a few YouTube videos, etc. I pay £10 per month though, which gives me far more internet data than I ever seem to use and far more call time, at an average of 20 minutes per day, than I use either. (I could probably get away with the £7 per month deal really).
GiffGaff is also cheap (and has plenty of fans here on AB):
https://mobile.asda.com/bundles