there are several tight gaps such as by Farnborough in the SW, Gatwick/Biggin in the SE
Having done a lot of flying out of Fairoaks I can vouch for the problems with the "Mig Alley" bottleneck between Gatwick and Heathrow / Biggin, particularly difficult in the evening, flying West into the setting sun - best avoided if possible. I suppose the same is true flying East in the morning, but I never got up early enough to try that!
It used to be straightforward to get a SVFR clearance when routing North from Fairoaks through the LHR zone, routing Thorpe, Ascot, Burnham not above 1000' - and similarly southbound. I've not flown there since the change to Class D, so I've no idea if getting clearance for that route is easier or harder to get now.
FBW