Insulating ground floor damp wall which has more windows than wall!

[S.p.rivett]

We are currently renovating a house which is over 150 years old. We are at the bottom of the hill with a lot of water under us. We have created underfloor drainage in the room higher up and need to insulate that room and the other room next to it. Both rooms have large windows, 2 windows in one room and 3 large shop windows in the other. We can only do internal insulation. Any suggestions would be greatly received. Photo of outside may be on the houses fb page 45 High Street. TIA