Getting an NHS diagnosis for high-functioning girl- doctor recommendations

Does anyone out there have any recommendations for NHS doctors who are good at diagnosing girls (and particularly teen girls) with high functioning autism/ Aspergers? Working with a girl who has had initial CAHMS assessment and autism ruled out on basis that she presents too well and can have a conversation (classic girl flying under the radar stuff), and was then diagnosed with ADHD which completely does not fit and everyone who works with her, and family agree. We all believe she has high functioning autism so looking for a good recommendation for a second opinion- ideally NHS due to cost considerations, but will go private if need to. Will travel anywhere! Please help!  Thank you.