Best thing to do is go to raveguide.co.uk or something to search for a night that suits your taste.
Fabric is always a good one for your first time in town, and though its very different then it used to be, offers quality line-ups and a decent vibe.
Otherwise many of the traditional london venues have died out, Turnmills, the End etc, all great places that I loved.
Try Herbal in East London, Shoreditch for a good little club run by quality people. Just check the line up to see wah gwan.
The Coronet at elephant and castle does good nights every once in a while as well as the Arches at london bridge.
if you are here by yourself and are around on the 29 of May Ill be heading to see LTJ bukem at fabric, and room one offers a bit more jump-up slightly rougher stuff. there is a big group of us going to check bukem, feel free to message me if you wanna tag along.
otherwise on the 19th im checking the 'abunchofcuts' night ' we fear silence ' at the arches in london bridge which is on a deeper/liquid soul flex.
Good luck mate and enjoy your time here, its a great time of year to come! just avoid public transport on a hot summer day...