I used to be a mortgage underwriter.
Sounds to me like the surveyor is covering his own back. It could well be that there's been very slight movement, but as he's not an expert in this, he wants someone else's opinion. Same with D & T report.
This is not necessarily a major concern. You may find that there was some kind of movement way in the past, it's been satisfactorily repaired and it's now all fine and everyone will breathe a sigh of relief. Although with the comments about the current standards of maintentance being low, I can see why the surveyor might be concerned that it's not been repaired properly/at all - that's why it needs checking.
With regards to getting the reports, there's a number of options :
-getting the vendors to get one, if you've needed one, chances are any subsequent buyers will need one (should you not proceed for any reason). Problem with this is that they might go with the cheapest and not the most reputable.
-look in (eg) Yellow Pages for local companies
-ask for recommendations from the surveyor, the estate agent and the building society. See if there's a name that's common from them all.
But most of all, please don't despair - although this rings alarm bells I really feel that in these days of litigation, it's just everybody covering their own backs.
On another note, it might be worth finding out who they are presently insured with. IME buildings insurers can be somewhat wary of insuring if there's been previous claims, but the existing insurer will often continue cover.
hth