Winter Project - Repairing rear arches and inner arches.

I want to repair my rear arches this winter and the inner arches will need repairing as well.

The drivers inner rear arch is worse with rot at the rear of the arch near the seam that joins to the inner half of the arch tub and repairs that have already been carried out to the front of the inner arch. It is also rotten above the filler neck. The inner half of the tub has been repaired around the seatbelt mount and where the fuel pipes pass through and is solid otherwise.

I was looking for advice on what others had done when repairing these areas. I was originally intending to remove the whole inner arch from the tub (I don't really want to replace the whole tub) but I'm not sure how easy it will be to get to the spot welds as I don't want to remove too much outer arch and my outer fuel filler hole looks solid. Would I be better off just cutting out the rotten bits and leaving the rest of the good metal there?

I've trawled the net but can't find on awfull lot with pics on what others have done!

Thanks in advance.

Matt.