I have just fixed the F1 fault by pressing the red reset button which is next to what I will - no doubt incorrectly - term "the flaming cabinet (of doom)"
I'm not sure which model it is but I took off the outer (white) case, the inner (alu) case which is clipped in place at the bottom. I then, completely unnecessarily, took off the front housing of "the flaming cabinet (of doom)" and freaked myself out when, having pressed the reset button to the left of "the flaming cabinet (of doom)", the cabinet errupted to life with scorching blue flame!
Not sure how long it will last. My mate, Ed, who works for BG said that often the gas inlet valve gets blocked and so the boiler thinks that the incorrect size pipe is going into the boiler. So either you have to clean the stuff out of the valve or something else (Ed was going on a bit and I lost concentration when a robin landed near the window).
Hope this helps.
Vern, May 2012