You've probably seen the guide here but if not...
http://www.communities.gov.uk/documents/planningandbuilding/pdf/133214.pdfSee Paragraph 10 and 28. Ideally you should get something in writing. Perhaps try getting him to write you a hand written note saying he's seen the plans and is happy for you to proceed. If neighbours don't respond in writing to notification then officially you are meant to apoint and pay for a party wall surveyor to act on their behalf. Obviously that would be expensive and delay things.
Paragraph 5....
Quote:The Act contains no enforcement procedures for failure to serve a notice. However, if you start work without having first given notice in the proper way, Adjoining Owners may seek to stop your work through a court injunction or seek other legal redress."
So is he an old boy that's likely to be scared his house is falling down when you start hammer drilling the wall or is he likely to know what to expect? Is he likely to go running to his solicitor rather than speak to you first?
Do some prep... Make sure he knows it will be noisy and remind him again just before you start work. Make sure he knows he can come talk to you if he's concerned. If you will be out at work while a builder works on your house make sure he has your mobile number. Take him a bottle of something to "make up for the noise" etc.