It's been quite difficult to miss corporate info on managing menopause the last couple of years or so. My employer is claims to be menopause friendly. We've had a couple of (voluntary) sessions about managing menopause.
I'm in my 50s. I have friends on HRT, friends whose symptoms have included anxiety that meant they couldn't drive at night, night sweats, hot flushes. I knew someone who committed suicide because of her menopausal symptoms. So it can be very serious. But I'm in my 50s, and other than irregular periods, I've not really had any symptoms, so I don't think I'd be any better than a woman in her 30s to talk about it.
But you (and I) can read up on how a woman can be protected at work etc, what adjustments can be made. What adjustments someone needs will depend on their symptoms. If someone has insomnia (something I can talk about at length, because it's been my body's default stress response since school,) you might be able to adjust start times, if they've had a bad night, or provide a desk fan for someone who has hot flushes, or let them leave their desk for an extra break. If it's causing joint pain and there's a physical aspect to their work, then maybe a change of duties might be possible.
It's going to depend on each woman and each workplace. You can't let a teacher come in an hour later if she has a class to teach, or at least not without revamping the whole timetable. But it's quite easy in my IT support department.
The TUC has some info - https://www.tuc.org.uk/menopause-work
As does ACAS - https://www.acas.org.uk/menopause-at-work
My union also has menopause information, so if you're in a union, you could ask them, and HR, occupational health. Some workplaces have a menopause policy, so you should know what's in that if your employer has one. (Previous employer said, not needed, it's covered by other policies around employee health conditions.)
Her thinking you're too young is just stupid. I've got a team member with a chronic gastric condition. I don't need to suffer it myself to be able to agree reasonable adjustments. He needs to tell me what the effects are that affects work and what he needs, which has mostly been time off for appointments and when he has a flare up, the ability to just go to the loos as needed, even in the middle of meetings (which could be an agreement a woman with flooding perimenopausal periods might want.)
Plus there's no harm reading up on what menopausal symptoms might be, so you'll be better prepared yourself, when the time comes.