So, Nat and I stayed in our caddy in a Layby about 10 mins drive from the pub. We did this for ~1 month and there was another RV type vehicle which stayed there too (and looked to be doing so for a greater amount of time). We didn't have any hassle.
However, one local pointed out that the police in the area didn't look favourably on you if you were found to be sleeping in a vehicle under the influence so advised that keys weren't obviously on your person etc. This wasn't a big issue for us.
TBH the camping was so cheap (the one with the Church) that I'd be inclined to stay there in the future (I no longer have a van). Is this for the Bank Holiday?