Dusty Dog, have a look at posting #18 #19 wheels are rotating, caravan is just being moved spot, no need to be serviced.Hang on Hutch the OP said I am not mechanical!
The giveaway for me is the 3+ years storage not moved , hand brake had been applied. I agree with you. Jack up one side at a time , hand brake off, move linkage as much as possible rotate wheel forward if possible At least two full turns .And yes the most important tool the lump hammer.
If the brakes are seized on I doubt the hubs will come off easily, not forgetting the hub nuts are one shot and must be replaced.
Buckman’s advice for a non mechanical person was correct imo👍