Should work whilst around London, make sure you use the latest frequency arrangements - the diagram in Pooleys will give you all you need. If they don't want to talk to you, they'll either hand you over, or recommend that you freecall somebody else.
The southerly bit, be careful of your navigation betweek Basingstoke and the coast - there aren't many particularly good features and you're likely to be a little close to Southampton CTA. Also, expect Farnborough to hand you over to Southampton who often will offer a zone crossing, so be ready for the question and have an answer ready. (It's actually quite low stress doing that under radar control if you're happy with the sudden change in routing.)
G