you are right to want the currency used to reflect the setting. No pressure to add more countries! You don't have to compromise your art and all that. If you had not intended on adding new countries. That kind of thing may be out of scope for your game idea and that is fine. There are a lot of factors that would go into making a new country feel unique and different from the UK in terms of gameplay, food names, character names, personality changes, interest changes, dialogue word choice, etc. My request would be just to add an optional currency symbol selector tbh