How demanding are the walks?
To answer this question we need to consider a number of factors.
Firstly the walk length: Sunday coach rambles have 3 walks organised, typically 5, 7-8 and 9-11 miles, Wednesday rambles, typically 5-8 miles.
Secondly how “hilly” is the route; walks in Nottinghamshire and in Leicestershire are relatively flat and so involve only very modest climbing. Derbyshire and Staffordshire can be much “hillier” and hence more demanding.
Thirdly the terrain underfoot; firm ground with short grass makes for easy walking but rough, stoney or soft, muddy ground makes for much harder going. Also stiles can be quite common on some walks.
Fourthly, weather conditions on the day e.g. walking into a strong headwind with driving rain.
And lastly the pace e.g. the longer Sunday walks must maintain a good steady pace (but not flat out) to cover the 10 miles in the time available whereas a 5 mile walk is obviously more leisurely.
“How demanding?” is clearly a complex mixture of the above factors. At one extreme is a 11 mile “hilly” route over difficult terrain in the Dark Peak, and at the other, a gentle stroll of 5 miles over firm ground near Nottingham.
An experienced walker used to crossing moorland and hill country could happily join the longer Sunday walks, somebody new to walking should start with a few of the shorter walks.