Hi,
I know how you feel. I am doing a PhD in computing and my topic is social networking. I am going to start write up in January and am not looking forward to finishing. What sort of job are you looking for ? Have you tried going to the carears office to discuss what you might like to do. Start talking to your supervisor about jobs and opportunties. They may be a chance to do a postdoc in your department or get a grant. Try looking at departments that deal with e.g Human computer interaction or image processing.If you want to look for an industry job ask e.g the person that deals with placements for undergrads because they will have a list of companies that you could ask.
Even though I am nearly at the end of the PhD, I find maths and programming hard but remember that it may just be the panic talking. If your supervisor did not think you could do it, they would not have let you go near writting up. You can do it, you just need to clear your mind and worries maybe by talking to supervisor and making a plan on how to job search. My supervisor is trying to get me to relax because he said that when I am stressed , I am very tough on myself and that does not help when doing a PhD.
Hope this helps :-)