Thanks for that. Looks like it's going to be a new ironing boardI would look at replacement rather than cleaning. While you could abrade away the rust, the surface seal has been broken and it will rapidly rust again. Otherwise consider covering it with expanded aluminium sheet, that will let steam through but provide a solid surface. You would need to cut the sheet to size and fix it in place.
Personally I’d rub it down, then spray it with a hardwearing paint from a rattle can. Something like enamel or Hammerite.
You’re right, sorry I should have specified high temperature enamel (VHT) the sort of thing you’d use for car engines.I'd do the same but using a heat resistant paint.