A surveyor can be anyone that’s not a party to the matter, but they should:
be impartial (eg not already advising on the proposed works)
have a good knowledge of construction
Note that you cannot act as your own surveyor. If your neighbour refuses or fails to appoint a surveyor, you can appoint one on their behalf.
It’s best practice to find a reputable, professional surveyor using The Royal Institution of Chartered Surveyors’ (RICs’) Find a Surveyor service.