Your best bet is to join the LP Fencing Forum at
www.fencingforum.com and post your question there - lots of well informed people around.
In short:
Foil: Salle Paul, Salle Boston, Sussex House - all London
Manchester Fencing Club, Salle Kiss - Manchester (come say hi if you turn up...)
Birmingham Fencing Club in (oddly) Birmingham
Edinburgh Fencing Club in (wow) Edinburgh, please note this isn't in England!
Epee:
Haverstock, London Thames, 126 in London
Reading
Edinburgh
Northumbria Uni in Newcastle is excellent and may let non-students fence