Loss of Training Fees Insurance
Try Traffords, they advertise in the back of some of the magazines. I had Loss of Training fees insurance which covered me just in case I didn't make it through the course for the type of reasons you mentioned.
When I got my licence it was a nightmare trying to find someone who would give me loss of licence insurance when I wasn't actively employed using it. I contacted BALPA Financial Services who managed to sort me out. As I explained to them, if I lose my licence for any reason I have still invested a lot of time and money into it and with the industry post September 11 a lot of my colleagues are in the same position as myself, looking for that elusive first job.
Hope you can find what you are looking for, It gave me peace of mind to know that I am covered.
One other thing, if you are not a member already, I would recommend you join BALPA (British AirLine Pilots Association)