You could try contacting www.haynes.co.uk and ask if the have a manual on caravanettes, or contact on go to your library and see or ask if they have reference manuals on caravanette.
Meanwhile I assume the seals you are talking about are around the roof section and are brittle in places which prevents a proper seal like the ones around the caravan front boots and the door. If it is like those they might be pushfit type which you could possible obtain from a service centre for caravans.
Bob
September 2008