There are four signed routes from coast to coast within striking distance of Sheffield:
- Trans-pennine trail – Southport to Hornsey. Mostly flat apart from the Woodhead Pass. Surfaces are variable http://www.transpenninetrail.org.uk
- Way of the Roses. Morecambe to Bridlington. Quite hilly on the western side & the climb out of Settle is not for the faint-hearted. http://wayoftheroses.info/
- C2C. The most popular and well-known of these routes, Has on-road and off-road options. http://www.c2c-guide.co.uk/ One of the optional start points is St Bees you’ve presumably looked at this. Plenty of long-drawn-out hill climbs.
- Hadrians Cycleway – follows Hadrians Wall ofcourse! http://www.cycle-routes.org/
hadrianscycleway/
Take your pick!