I live in Redhill but luckily right on the edge in a nice green part 8). I seldom go into Redhill town centre as it is not that pleasant, particularly at night. Reigate, although stuffy :-), has nicer parks, restaurants, pubs and feel. It is full of accountants and city escapists but it still has a bit of the old town vibe left if you make an effort (I grew up in Reigate).
Commuting from Redhill is easier than Reigate but trains have been a bit of a mess lately and it depends where in London you are going to. I go from Earlswood as it is closer but trains tend to be slower.
Doorstep riding is pretty good considering and there is a thriving biking community particularly if you like beer. I generally night ride from home and make trips to Leith/Holmbury/Pitch/Winterfold for day rides (25 mins in car). Boxhill, Headley and various commons and heaths are the local riding focus.