The next best option after Tiverton (outdoors, 10th only) and WORM (indoors micro only) you have is Caldicot...it's indoor's and runs every Friday evening (all year round), racing starts at 8pm...only down side is it's just the other side of the old severn bridge.
I drive over from Weston as well, it's about 40 mins usually, and we run mostly 10th offroad (2wd or 4wd) and micros. B4 is popular choice for starting out, and what I always suggest as good choice for 10th scale offroad, as it's also a car that can grow with you as it still runs in the A finals at the nationals in the hands of some of the best drivers in the world.
We have a good number of newbies right now, so there's a race for every ability. Tons of advice available and the shop that's usually at the club sells the spares, which is dead handy.
Dan and Si osbourne are regulars as well, and we have quite a few who make the trip over from this side of the bridge to go.
The South West doesn't quite have the numbers or tracks (currently ;-) of some other regions in the country, but a few options for you to pick from (quality not quantity ;-) )...or just go to all of them once the bug has bitten, as we all run on different days!
We have a section on here, and our own website...
www.caldicotrcracers.co.uk
Plus some vids on youtube if hunt them down! I have a channel on there called BluePinkyRC with some vids, but there are others on there as well.