Fan oven & light not working on Leisure Cookmaster 100 - How can i fix this?

I have a Leisure cookmaster 100 range cooker. The Fan oven stopped working mid way thro cooking. I assumed it must be a fuse as the convention oven & grill are all working normally. I have now noticed that the clock has gone out completely and I know that the clock directly links to the fan oven - making it work or not. How can I fix this? I can't see anyway to get at anything to even attempt to look - screws are enameled over etc In your opinion - is this going to be expensive to fix? Or at least how would I go about starting to sort it out. Many thanks