Thanks for the replies / suggestions. I've been having a look at the Denfords just to get an idea of what they're capable of - I was originally put off having seen them in many schools, but I've seen a few threads where the electronics have been upgraded, the enclosure ditched and Mach 3 installed & they appear to be quite sturdy / accurate machines for the money and relative ease to getting started. The Novamill on ebay looked interesting, but I wasn't (and am still not yet) decided on what it is I should really go for - plus the seller looked a bit dodgy (cheap motorbikes, Bentley wheel rims and a mill from a school!).

I hadn't realised the Denford was basically a Sherline mill; I know someone that recently bought a Taig mill converted to CNC with 4th axis, which was a comparible machine and seems to be serving well to do very similar type of work to me. The small diameter tooling doesn't worry me - most of the jobs I have in mind will be using sub 1mm end mills, and I'm aware I'm not going to end up with a machine that can do everything. A build from scratch does seem to be the way to get everything I'm after, but it's a bit daunting & small mills do appear to offer what I'm looking for.

Thanks again - the suggestions / comments are useful and very much appreciated.