The dealer you mention is my local dealer and although my curant van was not purchased from them my previous 5 vans where, my parents have allso purchased 3 vans from them my sister one van and just two weeks ago my sister inlaw has purchased her first van from them.
In all this time and with all 10 of these purchases we have never once had a problem, i am fortunate that with my last two vans i have not needed finance but every other van i mention has been financed through glossop and we have never had cause to complain.
Glossop use Black horse as there first and prefered finance house, black horse is probably the largest caravan finance provider in the country and is a wholely owned subsidary of lloyds tsb so i doubt very much that you have been offered anything other than a perfectly legal and fair contract, the only exception to this is if you have for some reason been refused by black horse glossop will then with your permission look at other more expensive providers who less restrictions.
Having had many years of dealings with this company i have heard stories of people who go out on a sunday to buy a van only to cancell it the next day, the car industry has the same problem with these addicted purchasers, I am not saying you are in any way one of these people Tom as i don't know you so can't judge you but you have to understand that the van you have purchased was taken off sale the minuite you signed the paperwork so glossop potentially have missed out on selling to another purchaser whilst you hold the sale, with this in mind can you not see the frustration that they suffer from people buying only to cancel.
I do happen to know that you can cancel if the deal they offer is changed in anyway, my sister recently bought a new van only to be rang the next day and adviced that the re-payment was going to be higher than expected, she was able to cancell and had her deposit returned no problem.
In your case since the deal is as you signed and the reason for your cancellation is just speculative in that your wife "may" be made redundant i would expect glossop to allow the cancellation but i would allso expect you to lose the deposit you paid as per the agreement you signed.
It is sad when things like this happen and i wish you and your wife the best with regards to the potential redundancy but we all must understand that the dealer allso needs to protect his interest.