Hi Mark.
As mentioned, removal of as much rust as possible with a wire brush in a drill, grinder or a power file (very useful) is advised. I used FE-123 rust converter from:
https://www.rust.co.uk/ which seems to be quite highly regarded.
I also used their Epoxy Mastic paint on many of the suspension components and my floor pan - again seems well regarded.
Taking components off to clean them up makes life much easier too. You may find a local powder coater will sand blast and powder coat your components for you for a reasonable cost - I haven't personally used one, but many people advocate this method for a good durable finish.
As Richard says, Bilt Hamber also offer great products in aerosol form and their rust converter Hydrate 80 is also good stuff:
https://bilthamber.com/product-category/anti-corrosion/ There is a discount code too for TDC members.
Enjoy the de-rusting! Don't forget the goggles!
BW
MC