I have just pulled the van out to give it a spring clean but when I rolled it back the off side wheel rolled in reverse but it won't roll forward, any ideas?
When was it last serviced? I guess it needs one, wheels & drums off, bearings regreased/new seals/brakes serviced/shoes replaced as required, anything less than that & you risk being stuck beside the road. If you don't have the mechanical knowledge to do that call out a mobile caravan service person, normally £70 odd+parts for a chassis service.
A bit drastic but you can try hitching it up and towing it forward a few yards on a firm surface (it will just skid on grass). This may well jerk it free. Don't tow it too far or you may do some damage if it doesn't come away. If this works, you will still need to have it serviced to prevent it happening again.
Don't leave the caravan with the handbrake on. Once the steadies are down, release the handbrake. The steadies will prevent it moving. If left on, the handbrake may well seize.