No, please do not sign the consent form, ever! a neighbour only signs a consent form if they are happy with the neighbours proposals and do NOT want a Surveyor involved in drawing up an Award.
If you sign the consent form, you are basically agreeing to your neighbour cracking on with things under their own steam, with no-one looking after your interests.
By not signing the consent form, your neighbour can not start work until the Surveyor has prepared the Award, which sets out what works are to be done/ stipulates any conditions relating to these works and the hours the work can be carried out. It also means that if there are any problems along the way, you have the Surveyor to call upon to assist you/make sure the neighbour corrects any wrongdoing.
So, if you sign the consent form it means no Award and you are reliant on the neighbour doing as they said they would.
By not signing the consent form ever, you have the safeguard of the Award and free guidance of a Surveyor if problems arise.
I hope this clarifies things for you.