Ok, have read all your posts OP.
It's a roof. That's tricky, because even the fullest survey does not require the surveyor to climb up onto the roof. They can only go by what they could see from the ground and the windows.
Q: Can anything unusual, anything indicating the problem that's been discovered, be seen from the ground or the windows?
Ask the roofers who've quoted you for the work. Ask them all. They may say and notice different things. Listen really carefully to their answers. Take notes.
Q: What exactly did your survey say about the roof? It will have said something. Does what it says match what the roofers say can be seen?
Q: Did the survey make any recommendations about the roof? In particular, did it recommend that you have anyone look at the roof?
If so, even to check out something small, the surveyor will argue that you should have done that before purchase and that, had you done so, the wider problems would have been revealed.
Though, even if they did make such a recommendation and you didn't get it investigated prior to purchase, you could still have a case, depending on how precise they were about the extent of the problem, as they understood and presented it.
Next steps: Make notes on the issue, as you understand it. Your first step with the surveyor is to invite them over and talk through the issues with them. Take notes. Agree to nothing.
If you're still not satisfied, the surveyor will have a complaints procedure. Follow it.
Also, find relevant solicitors (try the law society website to find the right type, in your area - litigation, as well as anyone specialising in buildings). Phone one or two. They'll be able to give you an idea, pretty quickly, of whether you might have a case.
Previous owners of the house: you can check through the documentation you received when buying. All those tick lists. But, even if they lied on the paperwork, or made a mistake, there's barely any point pursuing them because, even if they were ordered to pay you, they probably never would and the court debt recovery process takes years.
Your solicitor: You lodged a copy of the survey with your conveyancing solicitor, didn't you? If so, then if there was a problem with the survey, that they failed to spot and should have done, you may have a case against them. They, like your surveyor, are professionally regulated and insured, so there is money available to settle any claim.
Good luck.