I realised that a lot of the "medieval" sounds that I was hearing in my head were lute sounds. Having bought one stringed instrument that differed dramatically from my usual guitars, I couldn't bring myself to buy a lute (apart from anything else they're expensive).

The compromise was to buy a nylon strung acoustic. Having done some surfing to see which ones were favourably reviewed, I settled on this one.

It plays well and has an action which isn't too unbearable for those of us who aren't classically trained. The sound is just what I was expecting and the fact that it's an electro-acoustic is a major bonus as I can record directly without having to mike it up