There are valid UK telephone area codes beginning with +44 178, but you need one more digit. For example, +44 1788 (or domestically 01788) is Rugby.
(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.)
There is no area code 2145, nor 02145, nor 21, nor 021, in the UK. There are no valid numbers beginning with 021 or +44 21.
UK area code 020 is London, but there are no valid numbers beginning with 020 4, much less 020 43. Also, the area code for London is just 020, not 020x or 020xx. There are no other UK telephone area codes beginning with 020.
Not a valid code.
All UK area codes begin with a 0. There is no area code 6010 in the UK, and there is no 06010 code either.
UK area code 020 is London.
There is no area code 20 in the UK
There is no 01134 code in the UK.
The country code and area code of Aberdeen, United Kingdom is 44, (0)1224.
Cambridge is in area code 01223, or +44 1223 from outside the UK.
In the UK, 0121 is the area code for Birmingham.
There is no area code 104 in North America (country code +1 = USA, Canada, etc.), the UK (country code +44), or Mexico (country code +52). If you are talking about a domestic area code, you need to specify the country. Telephone country code +1 is North America, but there are no valid numbers beginning with +1 0.
Until the early 1990's, area code +44 21 (or 021 within the UK) was Birmingham, which is now area code +44 121 (or 0121 within the UK). There has never been an area code +44 217 (or 0217) in the UK.