Hmm south east, well i disagree with the last posts, there are some more challemging airfields to visit, albeit sometimes only in certain conditions which will challenge you. In the examples i have avoided farm strips some of which are a real challenge but having the right aircraft is also a prerequisite.
So start with giving bembridge a go. Now bembridge is not an issue with lightish winds but it can be a really interesting ride in strong winds and even more so with strong cross winds. Expect plenty of turbulence and sheer approaching over the cliffs with more than 20 knots and more of the same with a 90 cross wind. Without boasting with 1,000s of hours i still get caught out and ended up going elsewhere recently after two approaches.
Alderney is a must the perspective just looks a bit differeng the first time and the wind can always be a factor.
Popham has been mentioned the dog leg over the petrol station is a challenge the first time
Manston is just a very good example of an accessible long and wide runway
Earls colne is the other end of the spectrum if you give the hard a go, shortish and narrowish.
Four all a bit different than the standard stuff for starters, i could go on!