Hello and welcome to the forum.
Avondale used to make good caravans, but sadly the ceased trading some years ago.
That shouldn't be a problem provided that no panels need to be replaced, because most on board appliances such as the fridge, cooker and heating are generic and spares are usually still available.
The main things to look out for are signs of damp, which is the biggest killer of caravans.
If the caravan was recently serviced there should be paperwork with the results of a damp check, but when you take a look before parting with any money, use your nose to smell damp and use your eyes to have a really good look.
Check inside where the front and back panels are joined, check in the toilet / washroom area and especially inside overhead lockers, under seat storage areas and around windows and skylights.
Look behind any curtains or blinds and gently peel back rubber surrounds to look for moisture or black mould.
After a good damp inspection
( take a torch), make sure that everything works ok.
Caravans usually have 2 electrical systems, 12v for some lighting, toilet flush and water pump, and some 230v sockets for the TV etc.
The stove should ignite ok using lpg and hot water and heating systems use lpg and sometimes electricity.
If everything checks out, have a look at any paperwork, service history and ensure that the vendors actually own the caravan.
If the previous owners include and accessories such as an Aquaroll, waste container etc so much the better.
Don't pay over the odds, the caravan is over 20 years old now.
Good luck and please let us know how you get on. 😊
Good luck,