It is a risk but it might be one you could take.
The survey is good as it points to structural integrity. But it ends here, it is a structural survey. Nothing to do with health and safety, this is covered by building regulations.
Building regulations have to be applied at the time of completion not for the standard that was required at the time of the original application.
So it isn't a case of getting the council to issue it. It gets so much more complicated. I know as I've been in the situation of getting a lapsed building notices up to date.
For instance on one of the properties I had renovated, a concrete slab under a foundation to an extension that would have passed 10 years ago, now wouldn't as the new regulations state for two story they must be thicker. This meant adapting the build or demolishing in part.
The devil is in the safety detail.
Having said this, if you can get a reduction in price to reflect the work you need to do to bring it up to the regulations it should have, and are happy to do the work then it's possible.
But unless your are going to settle for a devalued property when you come to sell again. You must have building regulations certificates in place.
Indemnity insurance may work, but be careful with the wording as this is an incomplete build in the eyes of the law.