yes uk campsite's good. If you look on camping and caravan club site you can click which ones you want too. Some C&C sites allow non memebers. If you start a thread with 'can you recommend a good (tent) campsite near Bango' then am sure you'll get some good recommendations?
If you are happy to be a little bit away from Bangor there are loads of nice campsites in Snowdonia, a lot of which are quite basic. Llyn Gwynant is beautiful and isn't that expensive if it is only you and one child.