Yes the fan is running! i'm pretty sure that it goes as far as the stage of lighting without lighting (don't think the pilot lights) then it keeps reseting itself until it actually lights sometimes taking up to 5mins. Once lit there is no problem with it cutting out because as soon as it lights...
My bro has a Ravenheat boiler which takes a few minutes to fire wether it be on ch or hw mode? When turned on it goes through all the motions of lighting i.e fan running etc but just doesn't light? it'll do this a few times then eventually it will fire (sometimes taking up to 5 mins to light)...