I'm local but utterly noobish; tell me more about this thing called Exmoor.
tis a strange yet compelling place (a bit like this forum). I occasionally stumble across it whilst propelling my velo between chez itchy and the abode of the dreaded dragon-in-law who abideth in Exeter (for Exmoor 'tis near there, but not as near as Dartmorrrr).
Anyway £19, which is a bit more than i'm used to paying for the average audax, gets you a BBQ on the preceding Saturday night, a 'free' T-shirt (which obviously hasn't been factored in to the entry fee) and unlimited jelly-babies/flapjacks etc. at the control points.
See this link
http://www.exmoorexplorer.co.uk/ - It's normally a good event which is predominantly off-road with good singletrack, especially if you pick the 'hard' route.. I think it's not overly publicised as it's limited to 400 places and it's normally full each year.
Of course there's nothing to stop you downloading the route and riding it anyway without paying......which sometimes i do outside of the actual event date.
Anyway you're fairly local so surely you've an MTB for the bits the penny-farthing can't hack??? Exmoor/Quantocks are regularly lauded in the MTB rags as being
the place for off-roading.