I'm a medic with little lab experience whose spent the past year failing dismally to generate interest in a neurodegeneration-based proposal. I've seen the odd MSc, but really want to get going on a proper doctorate. Any ideas? Some have suggested trying a standard topic and doing my bits on the side, but is this feasible, and how far from my preferred subject choice can I afford to stray?

Your best bet would probably be contacting people who work in the field directly. There are a lot of Medically Trained researches out there and I am sure if they think your proposal is good they will consider applying for funding for you as a PhD student to work on it. Good luck!

I similarly struggled to find someone interested in my own proposal and have now gained a place on a proposed topic working on something similar - however I have found it very easy to get support for carrying out some of my own ideas on the side. As long as thye fit in the story somewhere. Applying for advertised titles doesnt mean they are set in stone, there is a lot of flexibility once the funding is secured.