Best avoid the coast path in august! Shame as there’s a nice loop from heddons mouth to woody bay and back but it’s too exposed and narrow to risk meeting walkers round a blind corner!
The section from hangman hill towards heddons mouth would be ok with care, hang a right at holdstone down and do the glassbox descent to ladies mile near hunters inn then climb back up the road and retrace your steps. Have a look at the strava segments.
There’s a Tuesday night ride most weeks from the car park in Braunton at 6.30. Friendly, two hours or so.
Exmoor is close though. There’s a fun 90 min loop from the west end of the watersmeet bridleway, climbing up to the moor, following the doone valley river back to Rockford then along the watersmeet bridleway heading west back to the start.
There’s another decent loop from Lynmouth, up countisbury hill bridleway to Rockford, watersmeet bridleway then the lynbridge bridleway descent and road back to the start.
http://my.viewranger.com/route/details/NDY1Mzc%3D
The vertebrate sw mountain biking book has these routes in too
Worth looking up those areas on strava and checking out the routes people have ridden.