Like Happybunny, I am a teacher and so I gave up as early as possible at 29 weeks. The job was just too demanding and I couldn't manage being on my feet all day without passing out. Besides which, I kept worrying I wasn't doing a good job for all my A level classes and so on, so I was getting stressed.
As for keeping busy this is what I've done for the last 5 (!) weeks:
* Washed all the baby clothes, blankets etc.
* Put loads of maternity clothes and other junk on Ebay.
* Sorted out our books, CDs and DVDs and sold a load to the man on the market.
* Tidied up a bit.
* Packed my hospital bag (still to do the baby's!)
* AFTERNOON NAPS AND LONG BATHS
* Backed up all the photos and my school stuff on the PC.
* Carted all my school resourcees in boxes up to the in-laws' for storage.
Yeah OK it's not that much - but I think we probably need to relax as we won't have much energy when the baby gets here. I find it hard to sleep at night so the time off's been really useful for catching up with sleep too...