Tbf I got the stuff from my dad who used to take his own equipment to barbershops but I linked them down below:

Gillette 7'oclock sharp edge razor blades (my preferred)

Lion super stainless razor blades (not bad)

My Shavette (I couldn't find anywhere you can buy it seems like a really obscure brand)

Idk how to buy these things from the UK xd but I'm sure your local pharmacy/big grocery store would at least have some of the stuff. Amazon is always a good way as well.