Jinkster has a very valid point.
I did ATC, Duke of Edinburgh, martial arts and had a part time job. Whilst it kept me very busy, it certainly gave me plenty to talk about when I had my Admiralty Interview Board for the Royal Navy (which I managed to pass first time at 18 years old).
Don't underestimate the value of extra-curricular activities, but just make sure they do not detract from your mainstream studies!
Obs cop