It depends on which year your boat
was built. But I'd try Jeckells Sails
in the UK and also Z Spar, also in the UK (although maybe USSpars in Fl can help). Z Spars were definitely the Prout rigger for the last 10 years or so. I think Jeckells made the sails
. But you can also try Dolphin Sails in Harwich UK.
Failing that, one of the older UK published multihull books
. eg Pat Boyds Catamarans in Closeup.
Hope this helps
Richard Woods of Woods Designs
Woods Designs Sailing Catamarans