Appreciate your efforts at inclusivity.......but..
I get this route to be 108 miles @ 3 hrs 15 mins saddle time. I suspect that may be ambitious for that route on a Peak District weekend (unless it's raining).
Breaks down into 1st session of approx. 50 miles and 1.5 hrs and 2nd session of approx. 58 miles and 1.75 hrs.
Assume 1030 start post brekkie and assume 30 min stopover at Grindleford, providing it's not as busy as hell on a weekend (which it will be) and assume the above timings can be kept to, the best estimate to be back at NCMM would be
1415.
The reality, on above route, which incidentally includes some of the main tourist roads, is that those timings are optimistic (bicycles, horses, motorhomes, tourist traffic, roadworks etc). I think you would be lucky to be back for
1445
....and where are the extra fag breaks.
Not clear if this is a route in which you would participate.
Bottom line, doesn't really work for me, but I'm quite happy, as indicated earler, to sit this one out and wait for summat more suitable.
Once again, appreciate the effort and only playing Devil's Advocate with the above comments as opposed to being bloody difficult for the sake of it.