Every website should have a Contact Us page, here you could list several branches and contact details and include adding google maps for each branch.
You may even want to include your social media links i.e. twitter, facebook etc..
You may also utilise this page to state your company registration details:
For UK registered businesses your website needs to legally display the Company Information i.e. the business name, place of registration, registered number, registered office address and if it is a member of a trade association.
For sole traders and partnerships, the address of the principal place of business must be displayed.