plus there are so many different places for jam sessions and the like in the surrounding areas - in Streatham there's jazz on a Monday, in Croydon there's all manner of live stuff, lots of it just turn up with your gear and you'll get a chance, and hundreds of other places and genres.
Anything that improves your playing - and is fun - can only be a good thing. Even on academic courses, the ability to play well must help on application.