There are exchange such as coinbase, but I don't know if they offers p2p service and also Binance do offer p2p and I have used Binance before to trade on p2p and money sent to my account during trade and I had to release coin for them through exchange. But when Binance removed NGN P2p service then we moved down to bybit and bitget this where the place that offered p2p service and I have been using it without any problems.

Then for forum p2p service, since you didn't see any service then you had to create one maybe you get someone from UK over here to trade with but then you have to be very careful with the type of people you will trade with except for a reputable members and everything has to be on the server thread to increase transparency.