Our place is in a LFA - designated fragile.
We're at about 230m, and our land rises to about 260m - the soil is quite thin and very acid - we're next to a peaty grouse moor. It's windy.
Our grass grows fine - we can grow enough hay on some of our fields to keep our Shetland cattle herd in feed over the winter - we need to feed them for just over 6 months of the year.
The veg patch is about 1/3 acre; Veg - we can grow potatoes, peas, carrots, broad beans and neeps outside - also herbs such rosemary, parsley, chives and mint. More delicate veg - runner beans, french beans, some brassicas and salads we grow inside a polytunnel. Toms grow in there too with courgettes, squash and cues and more delicate herbs such as marjoram and coriander.
Fruit - apples, plums, gages, gooseberries and cherries are OK outside and raspberries are fine. We did try strawberries - but the pigs broke in and ate all the plants, along with all the Jerusalem Artichokes...
We couldn't grow cereals here - though a farmer a mile or so away and further down, grows barley for the Maltings,
The chickens don't care about the LFA, and the Shetland cattle will thrive on poor quality grazing without any concentrates - so they are well suited to our location and our way of farming. We've kept sheep here too - they're only interested in the next blade of grass.
It depends what you want to grow/keep - but just because a holding is in a LFA, doesn't mean you can't grow food successfully. The soil may need treating - ours is very acid, so that need correction for some things - but that's not difficult.
Don't let a LFA designation put you off.
Sue