(with a short snout preferably for less "ploughing").
Do not get pigs. Find another smallholder locally that does pigs, and work out what you can swap with each other so you get your free range pork without having your land ploughed.
Otherwise, Kune Kunes are reputed to dig
less than other breeds, but if you're set on British, and set on pigs, and accept some ploughing, then what about Saddlebacks? I have no personal experience of Middle Whites, but of the three breeds I've had (OSB, Large Black and Saddleback cross), I'd go for the Saddleback in your situation. The reason for that being that they are the fastest finishers of the three, and the ground trashing gets exponentially more after about 4 months. So although Saddlebacks dig as much as any other breed, they'd be doing it for less months as larger animals, so would do less damage.
The same may be true of Middle Whites, of course - I know people who send them away at 6 months for a nice lean carcase under 60kgs deadweight. And they have a shorter snout.
My Large Blacks dug less than the OSBs, but the Large Blacks take longer to finish, so overall the ground impact is probably similar to the OSBs.
Another way to look at it is, the ground will get trashed anyway, so which pigs will you like the most? Enough to compensate for the trashing of the ground? For me, that answer is OSB all the way, such characters
and so lovely to look at. Sounds like Berkshires may have the cute factor for you.