I'm currently doing a computer science masters and there is a pretty equal gender split across the different programmes I'm in classes with. However on my programme (specialism of Human Computer Interaction) there are more women - maybe 75:25 female:male but on the pure Computer Science programme, it is almost completely male. One of the men I have met on the pure CS course said he hates the compulsory HCI module as he isn't interested in the human element, he just loves to code. This seems to go with a lot of what I've encountered in working in the industry - men tend to like coding for the sake of it whereas women like what can be done with it.
One of my modules is introductory rather than specialised and is also offered to 3rd year undergrad students. Of the undergrads, it is almost exclusively male. Maybe 90%.
The difference may be that women who really love compsci will want to study to postgrad level which is why it is more equal. Or it could be, like in my case, they don't feel they are enough already. I avoid applying for jobs because I worry I can't do it and am essentially doing the masters to prove I can at significant cost to myself and despite having 6 years experience in the industry.
Of the postgrad women, very few are from the UK. The vast majority are from Saudi Arabia or China and have all come straight from the undergrad degree. Given how much more expensive tuition fees are for international students, it is likely they come from wealthy families and therefore their whole education has been private and they have had more opportunities so money is a huge factor.
Only 1 of my female lecturers has children and she always looks tired and stressed. During the school half term, she had to bring one of her children to a lecture and he sat at the back with a colouring book because of a childcare let down. Of the male lecturers, it is less likely that if their family was affected by a childcare failure, they would be the one bearing the impact and taking children to work.
In my second job in the industry, I was bullied a lot by senior males in the company. One didn't like the level of responsibility I had on a project and so constantly undermined me. My decisions were questioned and called out in a way that men's weren't. I was paid less than a man of the same age and less experience who had less responsibility.
I'm not sure that adds anything to the discussion, it's just a collection of my personal experiences of being in the tech industry and studying computer science now.