having previously owned a new Moody for 20 years, had the same issue every year with rust spots, so nothing new. Light sand with an angle grinder to remove rust staining and smooth, and a wire brush where pitted. Paint immediately with an anti rust, then an underwater epoxy paint, then antifouling with at least two coats on the leading edges.
Judgement call as too how bad it is or that you feel about it Andy.
I think Kevin and I are at opposite ends of the 'solution ideas' range, my need was certainly greater!
I've just had the entire hull & keel slurry blasted to remove 18years of antifoul and rust spotting on the keel of my D30 Classic. If you go for the full blast on the keel, have time and she's staying ashore for a while drying out.....my man blasted then gave it a day to go properly rusty [!!] as that gets all the salts out of the metal, then dry blasted it followed by primer. I'm epoxying and antifouling in the spring. If you're Solent area based, I'd highly recommend Marty at Randell Industrial Services.
I have a Dufour 365 (2006) and had some rust patches on the keel as well, I used a tercoo wheel (not a grinder) to take the rust off to the metal, used an epoxy sealant which bonds to rust and then a primer on top of that with antifouling over the top of everything.