All the London railway stations :
Chorleywood is on the Metropolitan underground line which has large steps / gaps; although the newer Metropolitan trains do not suffer from this. The Chiltern Railway is partially accessible to wheelchair travel via ramps - but there are no boarding ramps available. See pictures and further accessible transport in London detail from links below.
Underground lines : Metropolitan, National Rail Chiltern Railways
AccessAble Access Guide :
Accessibility friendly : Partial. Northbound towards Amersham or Chesham (A step 277mm/gap 53mm), southbound towards Liverpool Street (A step 230mm, gap 40mm). New, more accessible trains are currently being introduced on the Metropolitan line. The step and gap onto the train will vary. If you require level access onto the train, you will need to board a new train.
National Rail station has step free access via a steep ramp to both platforms, including access to the subway in crossing platforms. There appears to be a less steep ramp from the car park to platform 1. There are no boarding ramps available.
Level access between street and platform.
General description : See wiki
More comment :
National Rail Map and guide
Inclusive Britain Station Guide