This Boat has sailed im afraid ! Land and new builds is the way to make real money , i started developing in '93 at the bottom of the recession when you really could earn money from turning houses , there are no margins now unless you just play at it . As for doing the job yourself , forget it , you have to turn the money quickly or you just dont make a profit , its a very fine balance !
Avoid capital gains tax by living in the house you renovate or at least renting on the quiet while you do it , as long as its your principal residence you pay nothing . I started a ltd company to cover myself , only pay 18% income tax and all the bills go against that , never paid any real tax and haven't done too bad
Good luck !