Don't do BTECs this coming from somebody who has done one, and is now unemployed.
Most universities don't accept them, and employers don't care much for them.
Do A levels (A level maths would be good) then either Uni or an High level Apprenticeship.
A lot of people want to do apprenticeships, she will be against people older than her and with possible previous experience in the role. To get an apprenticeship you have to convince an employer that you feel passionate about the role and that you are worth spending 4 years of teaching and funding on.
I also found it really hard to decide what to do at 16.
I would recommend you put together a short list of jobs she is interested in and then try to get her some work experience, this will help her make a better choice. Maybe even miss out a year for this.