If I were going to do the Hadrian's Wall Path again, I'd really probably only do the middle bits from Black Carts (down the road from Greencarts Farm) to Banks (or vice versa) -- so I'd certainly come back to Greencarts!
We stayed in the bunk house, which was totally lovely and was a great place to stay for a night while we were on the Path. Sandra was super fun to talk to, and the accommodations were very adequate for our needs. There was a great atmosphere there, because in addition to the B&B, we were in the bunk house and there were lots of people camping as well. The bunkhouse is for the people staying in it, and the campers had their own facilities -- so for basic accommodations, it was great and we felt like we had our own space.
We were able to order an evening meal from a lady on another farm, which was delivered to us, and then we would've been able to have a full breakfast the next morning had we gotten up earlier, but there was self-service available and we got on our way well.

We took the bunkhouse option. The B&B (in the main house) was full. And there were lots of tent campers spread around. B&Bers ate in the dining room in the main house while campers were on their own (I assume). We bunkhousers had breakfast fixings brought to us the first day but a cooked breakfast on the second day. Usual English breakfast. We ate in the large kitchen area on the main floor.

The bunkhouse has 2 bedrooms, each with several sets of bunkbeds. There's only one shower, which wasn't an issue for the three of us but might be a big issue if all beds were spoken for.

There is one toilet and it's downstairs next to the kitchen. So if you're someone who needs to potty just before bathing, that would be a problem.

Sandra is welcoming and nice. The rooms were standard B&B room, but en suite and nice hot shower. Tea & coffee making in rooms and lovely garden area in which to take a drink. Breakfast was nice, we even had smoked salmon. The B&B is out of Chollerford and so food would have been a problem, but Sandra organised that at another B&B , which we thought was pricey for what we received. Also we were promised a vegetarian option, but there wasn't one on menu but one was made. I have given a separate review of Walwick Farmhouse.
Overall this is an OK B&B for walkers.

Very welcoming reception at working farm. various levels of accommodation, from comfortable B & B rooms to camping barn. Quiet peaceful night. Spacious shower room. Dinner is arranged at very smart neighbouring B & B - picked up by car. £25 for 3 courses but can have just one or two courses without any problem. Good range of choices - the homemade pate is the real thing and the local lamb was scrumptious.