Installation was straightforward. Migration was not. There's plenty of sites out there that will tell how to format a Blogger export so that Movable Type will read it, but try as I might I couldn't get MT to parse it correctly. Even more frustratingly it would tell me had been successful, but no entries would appear.
The solution was a little arcane, so I thought I'd post it to help others in the same boat as me.
In short, it seems MT is very picky about line endings. I'd been saving the import file on my Vista laptop, which of course then puts a Windows standard line ending on it, which in turn caused MT to throw a wobbly on upload. All I actually needed to do was download Notepad ++, change the line endings to Unix format and the encoding to UTF-8 and everything worked.