Roof replacement

Happy new year all. We lost some slates in the wind over new year, from the highest point on our house (of course!). This has been fixed but the roofer who came out (Aaron from ACG roofing) took some video recordings that very clearly show the poor state of repair of our roof, which hasn't been touched in 25 years (loose slates, crumbling parapets and masonry, ridge covers that move etc). The tiles are 

He's quoted us for it, but I'm keen to get some more quotes so am following up with a few of the roofers who have been recommended here over the last few years. I'm also interested in what people have paid for a full roof refurb recently - if anyone willing to share do please feel free to message me.