I live in Weston and know WORM. As far as I know the only 1/10th track running anything in the area is Tiverton...I believe they are pretty much the South West region as far the BRCA are concerned.
They run every few weeks all through the summer and shut down during winter I believe...
Since I used to live in Newport I help run Caldicot club, which is literally a stones throw from the old severn bridge...but on the welsh (expensive) side. Since Caldicot are a WRCA region club (welsh region) I've been running in the welsh regionals and haven't made it along to Tiverton this year, but Dan Harding races there, he's a worm regular so maybe speak to him about it.
As for the Welsh, turn out is relatively small but improving and driving standards very mixed and also improving with the extra numbers, so would love to promote it over there. But the meetings are certainly not as established as the mid west and mid south regions are, and the series does go far west into Wales, so depending on where you are, the mid west might still be your best bet.
If your near Weston though, me and a few others from the area make the trip over to Caldicot on friday nights for 1/10th (or micro's) indoor offroad antics...thiking about it, if you've been going to WORM, then probably know that already as Si and Dan and Caldicot regulars

Shameless plug done anyway