Hiring a surveyor is optional not a requirment, but it is highy advisable.
You can have a survey done at any stage in the process, even hiring one to accompany you during your initial viewings
Normally however a surveyor is hired once an offer is accepted or after the mortgage is secured.
There are 3 types of surveys you can choose from: valuation, home buyers and structual.
A valuation survey will be carried out by your lender and will cost around £200.
The most popular is the home buyer survey which will cost £250 to £500. This will be an inspection of the visable parts of the house so they will not lift floor boards of knock holes into walls to check the pipes or damp.