After some work - we've finally got the bottom part of the garden (the bit next to where the pool was) in a state where we can plant a lawn. We've hacked out I don't know how many bushes, trees and bamboos, mulched them into compost (with the fantastic Bosch tree chomper) and killed most of the remaining foliage - none of which was grass. We did this over the winter and got rid of all the remaining rubbish in about 40 cars loads to the local dump.
This was followed by a rotovation, an epic stone hunt (the kids helped), burying of some pipes to transport water around the garden, and days of raking to try and level out the bumps. Along the way we found a water source (the same that flows through the village), a barbecue and paved bit, and an old border (which now has some tomato plants in it). We've added a swing set, a sandpit and a little wooden house for the kids to play in.
The grass seed is now sown according to Alan's careful instructions, so now it's just a matter of watering and hopefully we'll have a new lawn in a few weeks!