Potterton Netaheat 16-22 Wont Fire Up?

Hi Ive had this boiler for many years and recently we had some bad weather, since then it wont fire up. I dont know if this uses a pilot light or not but if it does its out!

When I switch the heating or hot water on the boiler everything makes the right noises it just doesnt fire up. I had a new fan fitted about 18 months ago and it had been fine up until then.

Any help would be greatly appreciated.