How exciting! I have a couple of slightly cheating ideas for camping:
I too was nervous about my first holiday alone with ds (now 12). We went camping but took a very good friend who was single, and had no-one to holiday with, and has known ds since birth. We had a great time and shared the costs.
Another option is to go with a friend who also has children (my second holiday with ds!). You are then support for each other. My friend is married but her husband works very long hours. It was more fun for the kids too. Again the costs were shared as were the driving, cooking, childcare.
The third time we went away, it was just the two of us. We stayed in a campsite with a playpark and I camped as close to that as I could. DS played in there (within sound and sight) while I pitched and took down the tent - lots of practice at home helps you do this yourself. You can brace the opposite end of the pole against a stone, dip in the ground, a heavy piece of kit (cool-box for me) or a hnady tree.
It is my experience that, noticing a single parent, people quite often offer to help. A bemused smile and rueful upward glance encourages this. Tears give the wrong impression.
Otherwise, look out for farmhouses, etc, with small converted lets. They might be quite rural but they'll be cheaper for it.
Wales also has quite a few youth hostels. Youth hostels often have family rooms and kitchens where you can cook your own food.
Have a proper staycation: hire a cleaning-firm for a week (cheaper than a holiday) and plan lots of days at local beaches, country parks. Lots of councils do free or subsidised children's activities during school holidays eg pond-dipping, family swim-sessions (inflatables, no lappers), a range of sports and/ or adventure activities. Book pony-trekking as a slightly more expensive treat. All national museums are free so look for local ones as they also, often, have activities on during school holidays.
Alternatively, look on the home-swap threads on MN.
Have a lovely time x