I went for LSR in the end. The jacket was dropped in today, the work will be done tomorrow and be back with me by Wednesday. I'll post again on how well they do the work but if they can deliver on the speed they promise that'll do me nicely. When I spoke to them today they were friendly and helpful, and gave me one useful tip.
I've been using Nikwax TechWash and TX-Direct waterproofer, but it hasn't been stopping the water soaking into the outer fabric on my jackets. Apparently TX-Direct has to be tumble dried to activate it and many fabric bike jackets say "Do not tumble dry" presumably to stop the body armour being melted. LSR recommend Fabsil as this doesn't have to be heated to activate it. I'll be trying that on Wednesday when the jacket returns.