Your budget might limit the possibilities open to you. The areas you've mentioned are generally very expensive in terms of housing costs, precisely because they're in easy commuting distance of central London.
Didcot possibly isn't quite as bad as Ichkeria seems to paint it though. I've worked there, asking people loads of silly questions about their use of public transport, footpaths and cycle paths, etc. Knocking on people's doors, between 6pm and 9pm (just as they're cooking a meal, putting the kids to bed or watching Corrie) is quite a good test of just how friendly people are and I found Didcot folk to be amazingly friendly. (They're the exact opposite of the residents of Stratford, London, who get aggressive if you simply try to stop them in the street to ask them a couple of questions).
There's a really big (and surprisingly attractive) housing development, called Great Western Park, nearing completion on the edge of Didcot, with 3,300 homes. (That's where I've been supervising teams of people, knocking on people's doors, during several periods over the last few years). The influx of people into the town due to that development has resulted in its town centre faring much better than many others have in recent years, with far fewer closed shops and a generally upbeat feel to it. There are very good bus services in the area and easy access to both London and Oxford.
Don't rule Essex out of your list of possibilities. Chelmsford isn't a particularly attractive city but it's got an excellent market, two good shopping centres, a lovely theatre and loads of great place to eat and drink. Colchester, too, has quite a lot going for it. Going up into Suffolk, Ipswich is very popular with London commuters and very much an 'up and coming' town these days, especially around the Waterfront area (where there are lots of flats overlooking the river and loads of bars and restaurants).