Finally I have taken the last remaining 1 inch thick bog off the roof that the previous owner so thoughtfully left for me to deal with!
The roof was not as nice as I would have hoped, it's hard to tell in the pics but there was, rust pits scattered throughout the area, which I presume was caused by moisture sitting underneath the bog that shouldn't have been there. So after taking it all back to bare metal with an orbital sander, I applied a solution called rust blast and scrubbed the steel for about 2 hours straight letting it penetrate the little pits, It literally eats the rust away. then I purple strip wheeled the whole roof to bare metal again, then another 2 hours of rust blast solution, and surprisingly the roof came up quite nice !
My panel beater is now in the process of knocking out any dents, and giving it a thorough metal filing. My car will have very little filler and will be metal file finished where possible.
I will then spray the roof with Epoxy like the rest of the car.
I also used rust blast solution on the RH door skin. The LH door is being re-skinned.