Is 077 first 3 digits of mobile number in what city in UK?

A UK telephone number beginning with 077 (or +44 77 in international format) is a mobile phone. However, mobile numbers in the UK are assigned nationally without regard to location, except for ranges reserved for Jersey, Guernsey, and the Isle of Man. Otherwise, any UK mobile number could be from anywhere in England, Scotland, Wales, or Northern Ireland.

(The plus sign means "insert your international access prefix here." From a GSM mobile phone, you can enter the number in full international format, starting with the plus sign. The most common prefix is 00, but North America (USA, Canada, etc.) uses 011, Japan uses 010, Australia uses 0011, and many other countries use different prefixes.)