It's a huge undertaking and you have to REALLY REALLY want it.
My DD1 is a doctor, now a GP.
She knew that's what she wanted from the age of 4 ( very single minded child!)
Stellar GCSES needed, then careful choice of A levels... chemistry, biology maths.. (she also did psychology for some light relief) ..although they dont ALL have to be sciences, you do need a couple to be.
Voluntary experience.. help at a nursing home, etc, do some care work... just show committment to actually caring for people. And a blinder of a personal statement for uni... (getting a place is very competitive )
DD1 found the A levels harder than med school a lot of the time..she enjoyed med school, but the pressure is relentless, and lots give up. 5 years of med school, two years of Foundation (sort of being like an NQT) and they are thrown in it. Incredibly long hours, constant exams for which they pay ££££ and also they have to pay for insurance, memberships, etc etc
So 7 years just to be truly qualified, and then either choose a speciality or locum while you decide (that's what DD1 did) Then years more training for your speciality (3 for a GP)
Oh and you often have to move around, as a student DD was moved around the south west 4 times and she was lucky (can't drive for various reasons which made it even harder)
The pay is CRAP for the hours until you have worked for years. Social life destroyed cos the only people who understand are other medics . Burn out (and suicide rates) are high, although I think there is more support and acknowledgement of that now.
BUT after all that, if it's the only thing she's ever wanted... she should do it. My DD1 LOVES her job.. it's not a job though it's her life and passion. Her medic friends are an incredible bunch of intelligent, kind, passionate people, and she could never have not been a doctor.
But your DD needs to research for herself, if she really wants it. There are many other better paying jobs without the stress and responsibility of a doctor :)