a bit of advice please

hi guys ive got a 200 5dr disco and the gutter is non exhistent from the nsr door back and the box section behind it inside has no bottom the under side of the roof/gutter on the n/s has some rather nice sized holes also now shall i patch it or should i change the roof i know its a bit of a job but i thught the best way would be to slice through the pillars with a saw which way would you guys go thanks in advance

Some pics would help.

I believe the roof and gutter is a one piece section. Cutting through the pillars will leave the body very vulnerable to movement. Would need to be braced prior to cutting.