So this is growing arms and legs. Bear with me!
I replaced all the fuses, as I couldn't find a diagram specifying blower location.
Another issue had been happening prior to this, when first starting the car, I would have to wait for an audible electrical click down round the fuse box before power steering and electric windows would work...also my yellow triangle I have had for glow plugs wouldn't appear until this click sounded.
All very weird.
So with fuses changed, started car and everything back to normal, fan on, steering and windows straight away...for about 2 minutes, then fan stopped again.
Is there a relay affects windows steering heater?! I guess something is causing fuse to blow.
If anyone one can give me somewhere to start looking, it would be greatly appreciated, Adam