LondonMosque which is located at Regent's Park. If you take an Underground tube, you need to stop at Baker Street station.From the station you either can walk or take a bus. It was about 20 minutes walk from the station,but if it was your first time in London,it might be a bit hard to find the Mosque.So, please don't be shy to ask anyone over there. If you're lucky,you'll find muslim people around.
There are bookstore in the mosque and also a restaurants where you can get curry lamb and briyani rice. It won't cost you to much...