Dave presumes that the middle of May is the preferred time so he proposes either Tuesday 16th May returning Thursday* 25th May or Friday 19th May returning Sunday 28th May.
The itinerary would look like this;
Tuesday or Friday ..... Amorique (ferry)
Wednesday or Saturday ..... Kermanac'h ( Gîte d'étape) **
Thursday or Sunday ..... through until following Tuesday or Friday (6 nights)
Dave suggests this is spent at his house in Cahéran or the Gîte d'étape in Josselin. Six at each but more could be catered for at the latter.
Wednesday or Saturday ..... Gîte d'étape at Kermanac'h
* Weekday sailings are always cheaper on Brittany Ferries, if Andy E and Mike's employers are flexible everyone will benefit.
** Routes to and from Roscoff can easily be varied to make it feel like a proper tour (ie. no covering the same ground)