Do you have Beck for History? He was away for half of our (A2) course too and the coursework took up too much time.
He's an excellent teacher though.
I've had him from years 9-13 and I've learnt so much from him. I got an A* at History GCSE with him too.
I actually loved all the topics at GCSE, esp. America and foreign affairs (Cold War etc). Have you been given revision booklets for each topic? We were given them and they helped a lot, especially as they had past papers included in them too. The great thing about History GCSE is that you don't necessarily have to understand everything. Just learn your dates and the important events and you should be fine!
The same Qs usually re-appear too, so if you prepare sufficiently the papers should be fine.
Oh, and those 20 mark Qs (I think it's 20 marks?) at the end of the America papers are a godsend! I learnt a set answer that the teacher had marked and I'd got full marks in, and just memorised it well, lol. I actually went straight to those last Qs at the start of the exam so I wouldn't forget my answers!
If you have any Qs I'll be happy to help too.