Thing to remember in the South East the soil type plays a big role in “MTB”.
The soil in the chilterns (north + west) of maidenhead is very clayey.
This is great in the summer long natural rides (but not much gnar). if you get a wet winter can easily become unridable. (its not been too bad this winter last winter was alwful).
The soil to the south of bracknell (ish) is much more sandy and there is some very good woodsy undulating tight twisty mtbing all year round. Swinely forest (almost a trail centre is here).
The bit in between Maidenhead and bracknell is flat and good for road riding.
The problem is there is no north south train line.
Train lines in the south east tend to be in/out of london.
Therefore there is the an east west train line.
I see no point for you commuting on the train your not going to be closer to better mtbing.
I would therefore suggest
1. live in maidenhead, in the summer evening you can ride out to good natural riding (there are some “DH” trails on Winter Hill)
You can then ride/drive to bracknell/sandy areas for forest riding when u fancy it.
2. Live further south ie Bracknell area ish.
You then need to ride/drive to work. You will be able to get out in the forests for good riding all year.
The train is not going to help.
You can see the areas for good MTBing under 15 on this map
UK geology
Alternatively look at this for areas for MTBing. There isan area norht of maidenhead near cookham which is good.
Strava Heat map