When bf and I took our holiday back in the Spring, Hadrian's Wall was on my list of must-sees. (Classics major.
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We didn't hike along the wall trail itself, mainly because we didn't have time. We stayed in Newcastle, and got an all-day train ticket out to the wall country. We got off in a town called Haltwhistle and from there we caught the Hadrian's Wall bus. It stops at several of the historical sites and other tourist accommodations along the wall route.
I would definitely recommend stopping at the Vindolanda fort, and also at the Roman Army Museum. Just wandering the grounds at Vindolanda took several hours and was enough to wear us out.
As far as finding B&B's, etc., they're thick on the ground out that way. You shouldn't have any trouble. There are a ton of websites for getting schedules, routes, lodging, etc. If you haven't found them yet, just Google it. Most had very good information.
Enjoy your trip, and watch out for sheep!