I love this forum

I feel so much better now

In answer to some of the questions that have been raised...
It is more of a physical thing than a technical thing, to play the octave I need to move my hand perpendicular to the keyboard (if you see what I mean). If I play directly onto the keyboard, I just clip the inside notes. This is why I can't do it fast. Every practice session starts with this one area trying to get it faster but I just can't seem to do it.
Unfortunately, in terms of physical capability, this piece was seen as the 'best of a bad bunch' from the Grade 6 repetorie (it's the Handel Gigue).
We've already had to modify it somewhat to allow me to physically play it but I leave it up to my teacher to determine when we can or can't do this - she seems insistent that this bit has to be played as an octave.
I've decided that I'm going to play it at a speed that is comfortable. I think I'm happier loosing marks because it's a bit slow rather than because it sounds terrible. Also, I've had a look on youtube (not the most reliable reference I know) and I seem to be playing it faster than some of the people on that!
Also, to be honest, I always think of this piece as a conversation between 3 different people. When it's played fast I think it sounds more like an argument so I actually think it sounds better at a slightly slower tempo.
Anyway, thanks again to all for your responses - most helpful

Also, phoned the AB today as I still haven't got my exam date and trying to get a day off work at short notice is almost impossible. So, after a bit of discussion and a centre change (5 minute drive to an hour drive) my provisional date is set for the 9th July. This is way after my last available date stated in the application but it does have the advantage that my teacher is back the week before so I can get some last minute advice