Originally Posted by contango

You can certainly do it without using motorways and major A-roads. The route might be a bit round-the-houses but it can be done. I just ran a route through bikeroutetoaster.com (taking a guess as to precisely where in Eastbourne and precisely where in Bath) and it suggested a route of 143 miles (it would need a bit of tweaking as it used a short section of the A303, a road people from the south of England will know isn't a first choice of roads to ride). That said you raise an interesting issue that I didn't notice anyone else touching on, namely route sheets.

If you've got people who might get separated everyone needs a route sheet, everyone needs to keep up with where they are on the route sheet, and someone has to generate the route, verify the route (ideally riding it to check it for bike suitability) etc. Then you've got potential issues of whether to take a short route over a huge hill or a long route to go around it, just how fast/busy a road needs to be before it's deemed unsuitable for the group, etc. If you (the OP) proposes a route and the riders hate it you've got another way they can criticise you for how badly you managed the whole thing.