Main thing now is to choose appropriate A-levels. The safest combo is Chemistry, Biology + one other rigorous one. Then work her socks off to get excellent predicted grades.
It is very useful if they can get some appropriate work experience before end of yr12 just to get some of that out of the way. Examples typical for applicants to medschool where I work would be 1-3 days shadowing someone clinical, plus 4 full days or 12 sessions in another suitable environment. Interacting with vulnerable people (disabled children, carer for family member(s), regular care home visits) is good. A shadowing placement in clinical envt would be ideal, but these can be hard to get, just keep looking & asking around. 6th form may have contacts to help.
Ideally keep a diary during the work experience to help her reflect upon it later, it's a common interview topic.
Reading medical-theme non-fiction in her summer hols is good. I recommend This is going to hurt (very funny), When Breath Becomes Air (sad & poignant) and Do No Harm (all 3).
I had a contact to help DD get 2 WE days shadowing GP & nurses at end of yr11. I sent DD to a Royal Society "So you want to study medicine?" event in London in yr12 (I think that's February time roughly); was free & DD said it was good overview.
Otherwise, DD didn't do any organising until June of yr12. Other than offering ONE talk, I can't say her 6th form did much either. By end of July yr12 she attended UCAS fair, went to 4 open days, signed up for UCAT & BMAT, organised a care home volunteer role. It will come together if is what they want.