help finding holiday accomodation for 8ish 16 year olds?

thinking of going away for a few days/a week either abroad to somewhere like france, or just by the coast to isle of wight/ bournemouth/ weymouth.
we need to find some cheap accomodation (e.g. a caravan) in an easy/ walkable to places location in one of these areas.
any websites or something or ideas of where we can go to find more info?
thank you, but preferably we didn’t want to stay in a hostel because we heard that these can be kind of dodgy..