Britain left the country without customs.

What you want to ask is whether there are any customs in Britain. Yes When Britain leaves the country, there is a customs office called the British Border Agency. The British Border Agency is the British government's agency responsible for border control and immigration management, and is responsible for supervising the British border, including customs, passports and immigration. When leaving the country, passengers need to show their valid passports or other travel documents to the British Border Agency for inspection and audit.