You can drive with an oyster card if you like,
the trouble may start when you are stopped and asked for your licence
Yes you are required to have an international driving licence and it should be easy enough to obtain, just a passport size photo and a small fee. There was a AA shop near me that issued them immediately, but its long gone now but I am sure they do it by post, also the post office. When I hired cars in the Philippines it was always a requirement.
