I love this part of town! The students seem to mostly hang out on Judd St, Tavistock Place, Marchmont St, Russell Square. You can do a good Blue Plaque trawl down Marchmont St.
On Judd St, the King of Felafel is good. And Patisserie Deux Amis does really nice croissants.
Skoob books, tucked away at the top of the Brunswick centre, is good for a browse.
Saint George's gardens is a hidden gem - I went there once and never found it again (challenged myself not to use a map)