Easy peasey, Calderdale / Rossendale
It's cheap, riding on your doorstep (literally), trains from Todmorden to Manchester, very good bus service (leather seats, new buses,every ten minutes) from Rawtenstall to Manchester. Probably make it to Leeds of Bradford by train. From where I am Lee Quarry is 10 mins, Gisburn Forest is 45 mins in the car.
Lakes, Peaks, Dale and North Wales all within easy distance.
Manchester on your doorstep with Leeds, Liverpool, Preston, Bradford all local along with loads of other decent sized towns.
Oh and Singletrack is based in Todmorden.
For a mountain biker with a life outside of mountain biking it don't get any better.
We are also central in the country with good motorway links and an international airport.
Job done, time to pack.