The bigger risk with the sheep is that they will start to eat the bark off the trees if they can reach it which could kill the trees
Personally I would be inclined to plant an edible hedge along the fence (things like hawthorn, wild rose, rowan, elder, sea buckthorn, blackberries etc, things that will be okay for the sheep to eat the leaves off, will provide lots of support for nature and you get the bonus of some berries off if you want it and if not the wildlife benefits. If you check the heights you can probably keep the hedge quite low (maybe not elder it grows so quickly!!)
Then it might be worth looking into forest gardening. This is a way of mimicing nature with your planting. So you get your upper storey (nut trees) your understory (fruit trees then fruit bushes) then the underplanting which can be veg and herbs and ground fruit or it can be flowers or a mix. You don't have to have all the levels, I skipped the nut tree level because I don't have the space.
So fruit trees with fruit bushes underneath and then I have underplanted with robust herbs etc which are good for the hens and can take the pecking they get. But you could have fruit trees, some bushes and then underplant with various bulbs so you get a succession of flowers for example.
Also if you are interested in edible gardening its worth looking at some of the more unusual things, for example magnolia petals are edible and the trees are beautiful. Also you can grow various types of pepper corns in this country etc.
With the fig tree keeping the roots contained is the important bit (as you probably know) so it fruits better, so if you are moving it from the pot to the ground don't forget a root bag for it.
I use keepers nursery for all my fruit trees, I've probably bought about 30 off them over the years and I've always been pleased with them, they are very knowledgeable about the right sort of rootstock and they have a wide range.
The other thing to consider is maybe a polytunnel? Because its not permanent like a greenhouse you should get away with it and that would give you the option for things like tomatoes, winter veg, and less hardy fruit like peaches, nectarines, passion fruit, grapes etc. They aren't as pretty if you are wanting something more visually appealing though but they do extend the growing season, give you somewhere dry to sit out in winter, and a useful place to dry clothes on a rainy day!