Political parties do not require local authority consent to sell or distribute literature (including newspapers) on public streets.
When selling Britain First newspapers in public, you may be hassled by council-employed jobsworths, but it is perfectly legal to sell party literature in public.
Politely ask council-employed jobsworths to leave you alone and carry on with your activities.
If the police give you any hassle, then show them this page and they will leave you alone.
Never back down and allow left-wing council jobsworths or police officers to force you to leave the town you are in.
This is the law you can cite when in any of these situations:
The Convention for the Protection of Human Rights and Fundamental Freedoms, Article 10:
1. Everyone has the right to freedom of expression. This right shall include freedom to hold opinions and to receive and impart information and ideas without interference by public authority regardless of frontiers.