If interested in walking or biking adventures in Europe (or in the UK, which is thankfully no longer Europe), you can do it the expensive way with Backroads or the cheap way with Macs.
Mac (obviously) started out doing Scotland walking trips, but has expanded all over. We're using his service for our Hadrian's Wall hike this summer. (They book your B&Bs and shlep your luggage. The daily hikes are on you.)