Let's offroad / mountain bike / mtb / ride dirt

Helpfully the Southwest trains website advises I use the national rail journey planner to avoid the engineering works, which insists the Waterloo-Guildford fast service is fine on Sunday. I might have to phone them tomorrow to check.

i was looking at dorking trains earlier and there is engineering on sunday.
maybe it doesn't effect fast trains or there is another route that doesn't go through dorking?