Before 2010, Google's email service was known as "Google Mail" rather than Gmail in the United Kingdom. However, it was then named Gmail. Since then, anyone creating a new Gmail account will get an @gmail.com address instead of @googlemail.com.
Google Mail account
If you already use Google Mail and want to change to an @gmail.com address, you can change to the matching @gmail.com username. Just go to your Gmail Settings, click the "Accounts" tab, and select "switch to @gmail.com". You can click here to change your address now. Remember that this link will only appear if you are eligible to change your address.
In case you make this address swap, it only affects your address. This means that your account settings, contacts, and existing mail won't make any change. Any email sent to your old @googlemail.com address will automatically be delivered to your new address. You can set up a default "From" address if you want to send mail as your old @googlemail.com address.