The Tube doesn't run all night long in London. So if you were expecting that London, being the vibing bustling metropolis, would have all night transport then sadly you are wrong. Be aware of this. Most trains have their last run between 12.30 - 1.00am. Don't get caught out as getting home otherwise can be a pain in the butt.
There are night buses if you are caught out after the Tube shuts but these are harder to work out and you may share the seat with an inebriated, smelly dude.