Horton farm is decent, I have a friend there who is happy. Yard is a bit scruffy but great turnout and people seem very nice and easy going. Not loads of hacking though.
I've been at Gasstons (on the headley border) which does assisted DIY. Yard is nice which amazing facilities and hacking, plus all the liveries are lovely so there is a great atmosphere. They are fairly controlling in how it is run though and the turnout is not great, it is restricted in the winter and if you don't look after your field they will ban turnout all together for weeks or months. Good place to go if your horse isn't fussed about staying in more over winter!
I know that there is a small DIY yard at the Durdans but don't know an awful lot about it. Theres also hurstfields in Walton on the hill but haven't heard the best things about it so possibly one to avoid! I'd also avoid Murray's Court and Garden Farm stables (both in kingswood), not run by the best people.
Hope that helps! Most of the yards in Epsom are part and full livery unfortunately.