I had a similar experience to TurboJ.
I did my IMC rating with them and was considering doing my CPL/IR there as well, however, I found it near impossible to get hold of someone to talk to me about it. I eventually asked if I could just book an initial lesson, just to get a feel for what it would be like - it turns out that they only have one commercial instructor per school (Blackbushe/Redhill/Shoreham) and at Redhill anyway, his schedule was fully booked for weeks in advance. That combined with the fact that their organisation at Redhill wasn't that hot at the best of times convinced me to go elsewhere. I went to BFC and never looked back. It's a shame really, because I only live up the road from Redhill and it would have been very convenient.
Redhill probably isn't the best base for IR training anyway. They have no nav aids at Redhill (even their ndb's U/S), and no useable airways nearby (compared to Bristol). You'd have to transit to Southend or Shorham each time before you even start training. Compare the london airspace to the airspace around Bristol and Bournmouth and you can see a much more distinct airways structure, and many 'useable' airports for commercial approaches.
Having said that, Redhill/Blackbushe/Shoreham are probably fine for CPL/Multi, and I enjoyed doing my IMC rating there, but I think I got lucky with a very good instructor who subsequently left to become a train driver
That was all about eight months ago, so things may have changed since then.