is it available outside of the uk and is it free?
The simple answer to both questions would be no.
On the other hand, it's not that simple, fortunately. The BBC services are publicly financed and therefore available to everybody in the UK, who pays the license fee. But there are no logins. If you are willing to answer the question "Did you pay your license fee?" with yes, when you should say no, you can get in. So if you consider this "free", then it is a yes.
Concerning availability: Most BBC services, including live streams from Wimbledon, are only available in the UK. But, as long as you are able to make the BBC website believe that you are in the UK, you get their content. So if you are able to set up your PR
) settings or to get a VPN connection, you get in. There are services for these kinds of things, paid and free. I have been using and highly recommend Unotelly.
So, if you know how, the answer to both questions would be yes.