Try the local Community transport group. There is one in Preston who also undertake vehicle repairs,they may have a spare. There are a number convertors in Lancashire who may be listed. There is also a s/h ambulance a bus dealer in Wigan who may help. I will try and find the names for you,but I may have chucked my contacts book away when I left the accessible transport game.
Got it! converter is called Jaycas and respond well to a sob story!
minibusjaycas.co.uk