Hi all,
Thanks again for the pointers and encouragement.
I tried to play with AWS, but their registration process barfed at the verification stage. However, Microsoft have saved the day: setting up a Windows Server VM with IIS was a breeze, and I've also made some progress setting up an SQL data source. I've deployed a couple of our web sites, although one is giving me grief (kind of normal when dealing with IIS, I find!).
One thing I have not got my head around yet is the charging. I was able to pick any Microsoft OS etc. and presumably the whole shebang (CPU/memory and their software) is charged for on a pay-as-you-go basis. But I'm not sure how I'm supposed to predict that in advance. Maybe I need to give in and read even more documentation.
Based on what I've seen to far, it's definitely worth a play (should anyone else be on the fence).