From speaking to the few people I know that have done an MD, there are some bodies which do fund researchers. You can get a list from the college. In order to apply for this funding though, you really need to do your homework, in order to convince them it is a viable project, and worth their time. This is where I find the stmbling block is, as even applying for these grants is very difficult, and in order to know how to put in a sound application, I feel you need to have a strong research backround in the 1st place, unless you can get some academic to help you with your proposal. 

Have you thought about doing an MSc, as it is much easier, as you can get your trust to fund this, and you can get 1 or 2 sessions off a week to do it. It would normally take atleast 2 years to do this way though. Perhaps though once you have an MSc, you can extend it to MD if possible, and it will be easier to get these research grants, once you have already demonstrated you have done some good work on the subject already. Chose your subject wisely though. 

The other thing I think you can do, although I am not sure, perhaps others will know more, is to make enquiries as to if there are any clinical lecturer posts available, as once you are in that academic post, you can do an MD. This would be a salaried post.

- Kate