Welcome from north Cumbria
I used to live near the North Devon Coast - near Lynton - whereabouts are you?
Your venture sounds great, and you'll have loads of support both on here and in person locally through DASH.
On the face of it, pigs sound like a good plan. Ivy could poison them if there was nothing else to eat but I think they will avoid things that are bad for them as long as they have plenty of choice. Tamworths are certainly good rotovators, possibly too good once they've done the job you want...
Most breeds will rootle as long as they're not overfed and become lazy, I think. My OSBs have been great fun and good rootlers, not bad on the escaping front (accidental rather than systematic breaking out
), Saddlebacks a delight - very easy-going pigs - but I do think the OSB is the tastiest I've had so far.
What can you buy locally? That'd be a good place to start!