Where to go for first time in camper van?

You could try the Club’s Freshwater East Site, near Manorbier in Pembrokeshire. It’s a coastal site, in a lovely location.

You need to tell folks exactly what your needs are to be honest. Will you need loos and showers, do you want electrical hook up, anything else? 
The Club’s handbook will list what each Club Site has, and if you want to save money, you might consider a CL (certificated Location) Many of these have lots of facilities. If you are brand new to things, have a good read of your Members Handbook, or browse help pages on here😁 Most things are very easy, and there’s always someone to help if required.

Enjoy👍

Cirencester Park wouldn’t be that far and is a very nice site, certainly all the mod cons, including regular visits by fish and chip vans and the like. It also has the advantage of having good availability in May and even some service pitches available.

Hi amwa, I've always found Practical Caravan magazine's Top 100 sites (now on their website, I think) supplement, a handy / good guide for suggestions for sites.👍

Enjoy!

Somewhere near home for your first outing so you can pop back (on a bike or a bus) for things you have forgotten. Then you can go further away when you have got everything in place. Enjoy your new vehicle.

You might like CAMC Pembrey, it's not too far from your home area, it's a good site with all mod cons, fairly level and you've got access straight into the adjoining country park and lovely beach. Town and shops nearby. Good safe cycling all round there too. You can always ask on site for help, other visitors are usually friendly!