Joined: 27 Feb. 2002
I am, Marie, but I haven't been to London for some years now, so I'm not quite up-to-date on the different tickets anymore. So I can't really say anyhing about it, for fear of giving you the wrong information. However:
I don't think there is any ticket called the rail pass. If it's London you want, you probably mean the London Travel Card. This can be bought for different zones, and at least one of these covers Heathrow as well, at least the tube line to/from it, but I doubt that it is valid for the Heathrow Express. The Express is probably a privately run train line. But I'm only guessing now.
If it's the UK as a whole you mean, then there are the different types of Britrail passes.
There must one of our British friends here who knows more about this than I do!