Hi I have kept NRs now for a few years and bred successfully from them. They are very confident and don't mind people at all.
I got lots of info from the NR Society which particularly goes on about feeding and the copper thing and to be positively paranoid about what you are giving them. On the other hand I also bought some other NRs from a different breeder who was more 'relaxed' and just gave them normal sheep crunch - the 'background' copper level is below the danger level - I had it tested by a lab just to make sure and it is totally fine to give them. Since then my ewes have survived well on crunch and grass and hay and are all in good health.
All in all though, they are 'flimsy' sheep compared to others. They have very little meat on their bones compared to other rare breed sheep and you may lose a few over time, they are not the most hardy, so expect you may have losses and then don't cut yourself up about it.
They are real scrubland sheep and I find them quite goat like (we also keep goats) in that they like an unusual amount of vegetation and indeed prefer it to grass. Just be careful if you are giving them tree branches and the like, know your plants. They particularly like Ash trees and Oak and they like the occasional oatcake biscuit treat. Their lack of meat is offset by their friendliness and handleability for the smallholder and it seems their fleeces are popular. They are prettier with their fleeces on than off - proportionally they are not as 'neat' as other sheep like Castlemilk Moorits which look like Rhoe Deer when shorn.
Good luck with your girls - make sure you don't give them a normal sheep lick or have one nearby they could get to (eg if you have ponies nearby). It could kill them pronto. They need a special lick from Dennis Brinicombe (spelling?) which doesn't have copper, you can order from their website but it costs around £45 - I bought 2 a long time ago and the second one has been sitting in the field unlicked pretty much, in fact it's probably out of date I should check. I'd just put lumps of rock salt around the place - you can get them from your local farm supply shop for cheap as chips.
All the best and photos please!