Thanks Babyboos. Those are great ideas and I can't wait to get experimenting. Once I recharge my camera batteries I promise to post a picture. As far as I can tell from the barcode sticker on the bottom, the cage is a FOP (Italian brand) Ted cage. It seems quite an old fashioned cage, with a deep plastic base and white wire top which clips on. The access isn't great. There are three small doors: two on the top and one on the front, but I can reach all areas of the cage from it. The shelves look good, but unfortunately they can't be arranged so they overlap properly. There's always a space on the higher shelf for the hamster to fall off, so I'll have to make do with one shelf.
Never mind. The guy also provided a few bits and bobs like wheels and see saw tubes, which is nice. They are all soaking now.
Once those are dry and disinfected, I will be all ready for a hamster. Hooray!