Hi Rob, that's a big step forward on your 5 year plan!
I'm not sure exactly what you mean by peat land - if you mean it's peaty soil, then thank heaven for your good luck because it will grow well (though obviously be acidic so may need liming for some crops) and peat mud doesn't stick to your boots at all! (Whenever I miss the sunny summers, I recall Wiltshire clay and the half-tonne boots you would be clumping around in as soon as the wet weather did come... and realise I am better off up here, even though we hardly ever get any kind of a summer.)
However, if you meant peaty moorland type ground, then read on.
Most people do not realise that an active peat bog sequesters more carbon than the same area of actively growing woodland.
If environmental sensitivity is important to you then you'll want to find out if the peat is active. If so, and you want it to carry on actively sequestering carbon, then there will be very little improvement you can make to it.
If it's already been killed off then, unless you want to explore reactivating it (which is not easy and cannot always be achieved), all you will do if you 'improve' it is release some or all of the carbon it holds.
Pigs and peat bog are not an ideal combination; the pigs' rootling will damage the peat and the bog will by definition be wet, which is not a pig's favourite environment. I was advised by the National Park ecologist that 2 to 4 pigs on my 500 acre peat bog would probably be acceptable, but not more. No that's not a typo, five hundred acres for a maximum of four pigs. (We had 400+ sheep on there too, mind. She might have let me have 10 pigs if we hadn't had any sheep!)
Having said all of which, there are fields in these parts which have been drained (vigorously!), ploughed and seeded and are grazed and mown for hay but which if left would revert to rushy dampness. There are times when the ground, even though it's drained, is too wet for more than sheep and certainly too wet for a tractor.
If you can be a bit more specific about the ground I will try to be more helpful.
As to your chickens, so long as they have a windproof (but ventilated) house they can snuggle together in and always have somewhere to stretch and peck about that isn't covered in snow or frozen solid (a barn or stable is suitable for the worst of the weather), and you can keep some water thawed for them, they should be fine.
Exciting times ahead! Good luck with it all.