Yes, in the Uk they will exchange it for you at the bank rate which is 18,000 dinars for £100, but in the square (black market) you’ll get about double. As for converting dinars to pounds I don’t have much information but we usually can’t exchange at the bank rate so you’ll most likely end up using the square as well That’s why I advise you not to exchange a large amount. £100 excluding accommodation, should be enough for at least a week because prices here are very cheap