Advice on maintenance issue with co freeholder

Olistanding

Hi, i live in a victorian house which is converted in to two flats which have shared maintenance responsibilities of the common areas. I live in the ground floor flat and have been told by the other freeholder that the roof felt needs replacing and the roof is leaking slightly.

I am keen to get a couple of opinions on how soon the roof needs refelting and the cost of any remedial repairs however the other freeholder is about to put their flat on the market and therefore is only willing to allow access for her friend (who is roofer) to patch it up.
Should i insist on getting independent opinions on this? My fear is that (i) we might get overcharged for the initial work and (ii) the problem might get worse if only patched up and i might be left with a difficult situation if the new buyers dont pick it up in their survey.
I only moved in late last year so dont know the other freeholder bery well which doesnt help matters
Any advice much appreciated
Oli