Thank you for your wise words , especially crimson96.
Thought I'd update you on what I did ...albeit a few weeks ago now!
I'm very pleased with the extremely cheap Brembos off Ebay - they seem real(?!) and for the same price as Pagids (£60ish pair). The only painted parts were the vents and the side of the hub(?) of the disc. The braking surface and the surface in contact with the alloy are not painted. (Apologies, it hasn't come up well in the photos). Basically, all the bits that go rusty on standard discs are painted.
Brake pads fitted too, and all is fine. I have only done the fronts as money is temporarily tight. Painted the calliper and pad holder to keep it all looking clean with black VHT paint.
Braking performance has improved, but is still nowhere near what I would hope. The nose really dives, but as scottyf suggests, that wont stop. I hope it will improve with new rear brake pads and discs but still expect it to nose dive a little. Just less so than at the mo.
With a big service looming, I'll have the brake fluid replaced. I didn't do a great job with that on my mountain bike, so best leave the car to a professional! I'm hoping that will improve bite and feel.
I'm no racer, so will do the rears and get some better tyres on in due course.
Thanks for the advice all!