USPS
Go to the USPS website (see link), pick whatever country you want to send mail to, select the weight and type of letter or package, and get your answer.
3- 5 Days
It cost $11.45 to send the package.
1 to 14 days or more
Approx. two weeks.
2-3 weeks
I sent a package from the US to england and it only took 3 days using USPS. ...
Ask in a post office in US.
Ask at a post office in US.
Ask in a post office in US.
A USPS postage rate for a 2KG package being sent from London to Birmingham would not be possible as USPS is a US company which operates in the US. It would be the Royal Mail or Post Office that you would use in the UK for sending packages between these two cities.