If you are just wanting to try one out, use it, and get a feel for it, then Rough Ryder makes good quality knives. I don't know about their availability over the Pond, but they are a decent budget user.
Something like this one would work, though I hate the ugly "R" stamped on the bolster:
https://www.ebay.com/itm/394413635656?m ... media=COPY
I recommend one with carbon steel blades though, if you can find it. The new Schrade and Queen knives are of similar quality. Frost has several that are decent users for under $15 US, but they also have Pakistani knives that are not worth carrying. You have to be careful with them.
Now if you want a better knife (and who doesn't?), any good brand name should be great knives: Case or Bear & Son for new knives, with Henckles (or most any Solingen manufacturer), Queen, Schrade, and Remington for used knives.
This post may not help, but I hope that it does.
Jesus is life.
Everything else is just a hobby.
~Reverand