Just an update following some emails with Alan Boswell.
Yesterday I achieved around 60° into wind at above 3knts SOG (no tide), which was my minimum speed requirement. Going to around 55° the speed started to drop quite rapidly.
I think two of Alan's suggestions that made the difference were putting both sheet travellers to windward with one reef in the mizzen (in 9-15knts wind).
Previously I would have got massive weather helm so I would reef both sails or let out the mizzen. This solved the weather helm but decreased boat speed. With just reefing the mizzen I kept boat speed and reduced weather helm.
I also changed the halyards from 12mm to 10mm on the main and from 10mm to 8mm on the mizzen which allows me to adjust them much more easily. The thicker ones where on her when I bought her and I think the top block gave too much friction.
Finally I think the new sails designed by Alan and made locally make a huge difference to the boat speed especially in lighter winds. Before I really needed 10knts to get going where as now I’m thinking of reefing in 10kts. The hinged battens in the pockets produce a very nice wing shape.