Thank-you for responding!
I'm also a member at Apex on London road (formerly Energie) but just renewed as Gym only as I never went to a single class there last year (did'nt appeal or schedule did'nt allow) so decided to save £100 and attend classes elsewhere..I had no idea it would be this difficult to get to a class at a council gym.
I'll take your advice and look into Crystal Palace and Lewisham but the time waiting for and travelling on public transport makes me inwardly groan just thinking about it!