Tell me about surveys please!

[snackattack]

What's the difference between the homebuyer's survey and the other one (can't remember what you call it?). How much do they both cost - roughly? Am looking at buying a house which has obvious cracks in plaster in an extension which is about 2 years old. Not sure if this is something to worry about or something that is due to building settling down (?? - what the estate agent said!)...
Thank you!

Homebuyers survey - basic description, not investigations (ie they don't actually look inside the house at problems or potential issues). A structural survey, as it suggests involves someone who has trained as a structural surveyor walking round the house, poking it and doing various tests if problems are noted - i.e. if there is a big crack, the surveyor will go outside and see if there is a corresponding crack outside and if so suggest work that may need to be done to remedy it.

How old is the actual house? If the extension has a crack and is only two years old it could just be settlement, but how wide exactly is the crack. If it's a hairline crack, see where it goes, does it go along window or doorframes or change direction, can you see light through it. If you look at the corresponding bit outside can you see a crack there? Look outside the extension, take a good look at ground level, can you see foundations sticking out of the ground (will indicate it's not down deep enough), does the floor appear level - take a spirit level etc.