I'm an 36" inside leg as well, and have done loads of 'research' on finding tights that are long enough for tall girls. I recently bought some adidas tights from Start Fitness, and they cover my legs ALMOST down to my ankles. I figure that put some long socks on underneath, and my ankles will be nice and warm in the winter. The Adidas tights are actually the womens tights - I was told to try mens tights, but found that apart from being bulky 'up top', they were too tight around the calves!and too short!!
I also tried some Nike trousers on; too me they felt more like gym trousers, as they were flared at the bottom, but they were definetlively long enough for me. Let me know if you find anything else - i'ts a pain having such a limited choice of trousers.