I've shot emails off to the three local sites to see whether they'll allow non scouty people on site. My best choice is a no due to being booked, the other two depend on whether they take non crb'd people. Failing that I have a field next to a railway line free to use, a much quieter garden or we could try our hands at stealth camping.
Two of the three have said no, so it leaves us with either my field (has a couple of trees suitable for hanging as well) and a convenient train station). Fires ARE allowed, my 60ft garden which is a little overlooked but again, fires are allowed and if the weather is fine we can always get the pizza oven alight though currently it looks like a bit of a bomb site due to the new path being installed or there's a couple of public woods which several are used for camping though I'm guessing not officially...