I was also intrigued by the 63 cut off! I'm nowhere near it yet but just very interested in the logic behind it - my parents are both in their mid-70s and can still do nearly as much hard manual labour as I can (just lacking the whole day stamina they once had).
Of course your dream is realistic. I think you probably need to consider the timing though. I guess once your husband finished medical school, he has to bounce around hospitals for a while being a house officer, SHO etc. until he gets a consultant post (if that's the way he's going?). Doesn't that mean you will have to move around for another ten years or so or is he able to pin down a rotation to a certain area so you can just be based there?
As the others have said, it's very difficult to make a living from smallholding so good thing your husband will have a decent salary to help fund it. That's our approach at the moment (we moved last May to our house with 8 acres) - my husband earns a good wage while I'm working on building up some income from our land and buildings. We're waiting on planning permission for a holiday cottage and if that works, maybe more, we've planted loads of fruit trees, veg beds are established, we have hens, ducks and geese, bees will be coming soon and at some point we'll look at bigger animals. If we manage to sell anything, great, otherwise we'll just reduce our outgoings. But all of this has cost a fortune to implement - and one reason we're holding back on bigger animals is things like the cost of fencing. Hopefully most of it will pay off eventually and I'm sure there are cheaper ways of doing things but my approach has been to get things built to last so I've paid lots of up front costs for things like poultry housing and runs which are going to take thousands of eggs to pay back (or hundreds of birds sold).
Good luck with your dreams! Meantime, as you know, there's lots you can do towards self sufficiency even without the land - I've always grown some veg in my back yard, however big and however covered in concrete.
H