That's interesting about Helen Sharman and you can see the point:
If people say "first british woman in space" the assumption by most people will be that a british man went first
OTOH and the reason people say first british woman in space - is that if you say "first brit in space" then people will assume male also
The best thing to do then is to say "The first Britain in space was a woman - Helen Sharman" or similar to make clear that she was the first person and also that she is a woman. If you leave either piece out, then it reverts to assumption that a man was first.
And of course this only comes up because when that guy went to the ISS HE was suddenly the first brit in space and everyone conveniently overlooked her. Then when this was pointed out, there was rather a (to my mind) convoluted technical reason for it, and rather than starting to say he was the second, they started saying he was the first official brit in space (or similar wording). Because OBVIOUSLY space is for men, and when things are very masculine, even when women do them first / better, there is often a reason found not to mention that, due to some technicality or other.
Annoying.
Of course now a TIM will be first and women will never need mentioning ever again. Phew!