The most important thing is the Public Liability Insurance. Such insurance will help you when accidently the property is damaged during your film shooting. There are several public liability insurance agencies in London who will help you in solving your issues some are mentioned below:
The next thing which has to be done is to contact the London Borough Film Services (BFS). You can either personally visit them, and fill in their application form or through online you can also contact them from the London Borough Film Services (BFS) Online Service
The location where you wish to shoot a scene may be a public property or it may be privately owned, but acquiring permission is the foremost thing. If you are shooting at such places you should first contact the owner of the place and try signing a legal document which includes the time during which you will be using their property for the shooting. If any loss occurs to their property during your film shoot you will be responsible for it.
The next thing after getting permission from the property owner is to inform the police and show them the legal signed document between you and the property owner. The involvement of police will provide a healthy and secure environment to you in which you can easily complete your task without any hassle.
Do not forget to mention the number of members in your crew along with their names, because you will also have to take the parking facilities. In London usually 5 members in a crew is considered to be a small crew while more than that is considered as a big crew.