It’s late, you’re still in the Library (or Union…) and you need to know how to get back to Wilson, huh?
From Autumn 2016, on Fridays and Saturdays, parts of the underground will run all night.
This is limited though, and currently only the Central line will be of any real use when living at Wilson. The closest Central line stations are Marble Arch and Lancaster Gate. See the night tube routes here.
If the night tube doesn't run where you want to be, you'll have to resort to other methods (and same if you're going out on a weekday).
The park gets locked on an evening, at sunset. You’ll get chased out by a man in a van with a megaphone; the road is open later, but we wouldn’t recommend walking along it at night – at points there is no path without going in to the park itself.
The 414 from outside South Kensington station stops on Edgeware Road, just next to Sussex Gardens. This isn’t a night bus.
If the 414 isn’t running you can either:
N97 from South Kensington to Hyde Park Corner and then N16 or 36 from Hyde Park Corner to Edgeware Road.
Or, from Church Street (High Street Kensington) the 27 goes to Paddington.
Take your pick. Lots of buses will get you back – you’re looking for “Edgeware Road” or “Marble Arch”. 159, 23, 6, N98, N7 all come from Central London, the first 3 pick up from Trafalgar Square (which, if you’re anywhere else in London, you can pretty much get a bus to…)