Linnet - my experience of Scottish surveyors versus English surveyours is that Scottish surveyors will say that "There is evidence of some subsidence but it has settled now - what do you expect in an older house?" and an English surveyor will say, "There evidence of subsidenc, you'll need to get a strucutral engineer in before we commit to anything and so that you can negotiate a discount - and there's a mine half a mile away so you'll need to get that checked out as well before you finalise anything".
Glasgow is riddled with mines, but the view generally is that they were so shallow that any potential damage would have shown up by now. I know you're not in Glasgow, but I'm just illustrating the difference in attitude.
Part of the reason is because in Scotland we are surveying before we offer, to see what we think the house is worth, whereas in Enlgand they are surveying after they've offered, to see if there is anything that they can use to negotiate the price down further - but it does casue the delays and chains, when things collpase!
I'd have thought in your circunstances, as you already know the proprt, a good housebuyers report would be sufficient. You can specifically ask him to chekc out something you might have a concern with- and you can also get a specialist in to look at sometihng afterwards if he highlights something.
BTW, our house has massive cracks in a couple of interior walls. We've had an architect friend look at them, and he says they are to be expected: it is a Vicotrian house built on shallow foundations and it is twisting - but that it is still sound (given that the exterior walls are three foot thick!) We've plastered over one of them, and when we next decorate the living room, we'll plaster over the one on the other side of the same wall.