Fault code F-08 should mean that the heater relay has welded itself shut. I had this problem on my hotpoint just out of warranty so it cost over £80. I left the machine pulled out from under the work-top because I knew the drain pipe would come undone if the "engineer" pulled the machine out himself and he wouldn't notice, so I wanted it over the edge of my sink. I also unplugged the machine. When the repair bloke came (several hours later when I was at work) he plugged it back in and it worked fine. £80 down but with 12 months warranty on his "repair".
It's happened a couple of times since then (I was looking for a better fix for it when I read your question but no-one else has mentioned this one!) and unplugging for AT LEAST 4 HOURS has worked so far (and again today). Don't just turn it off, unplug it and the software may reset like on mine. If it doesn't and your machine is not in warranty I'd get a new machine (not Hotpoint). You'll just throw money at it otherwise.
Hope this helps you
Nick
Nick
June 2008