Thanks so much Richard for all the helpful advice. So far I'm not anticipating packing in my day job! This is just a one-off. But I have realised that I've advised them to buy standard, and of course I'm really going to need Advanced. Which costs CONSIDERABLY more than this job will earn me. Of course if I was doing lots of it that would be fine. This one is so simple it really won't need Advanced - or is that famous last words? - so maybe for now I can use the single copy to maintain their database. If any more comes my way, I'll have to bite the bullet and buy myself Advanced.
There is no such thing as a finished database. Every one is a work in progress.