Mine would be if you like camping/caravanning to join the Camping and caravan club (or similar) that way you can use the certified sites and stay as low as £5 a night. We used to be members but didn't rejoin last year, will probably join again this year though? Plus dp and I used to stay on our own sometimes for a night, some are behind pubs. Or near to pubs.
Any other tips or budget places to stay? I used to think hostels but tbh cottages aren't much different in price. We often stay in a cottage, just booked one for Easter holidays that sleeps 6 for £350 for 6 nights. Plus it's in a lovely place by the sea.