@clubman you asked me if I had sorted out my Simplex derailleur. Well I hadn't and I wasn't going to but your right it will be a useful gear on such a long journey.
So I went on a hunt for some thin washers in the Loire Atlantic region of France today, I thought I could use a washer on the rear axle between the wheel and dropout. This should push the derailleur out enough for it to drag the chain onto the smallest cog. Will let you know how it goes. The bikes running well, saddles still hard, thanks @Big_Block for the info will give this a try.