Replacing flat roof for pitched roof

[bluebaron]

I have a 4m x 5m flat roof single skin (with piers) brick garage.

I am looking to replace the roof for a pitch design with dormer for space above And a sloping roof to the rear.
I attached plans below.
I can do a lot of the work myself but assuming structural calculations are done and wall plate is all in place how much am I looking at to get the roof done. I,m thinking probably a warm roof design, clay tiles, timber gable ends.
not counting the flat roof section to the side I’ll do that later.

thanks

 

[freddiemercurystwin]

You can still quite clearly read the address btw.