As someone who's a current University student and been through the application process and the like myself I think it's actually hard to tell whether GCSEs and AS levels really are 'worthless'. They used my GCSEs to assess English proficiency. My A level grades were more highly regarded here than they would have been in the UK (by a great deal as well). I got mostly Cs and that amounted to a rank that was the equivalent to an OP (Overall Position) of about 8 (which is quite high, and I needed to achieve a 13 to get into the course I wanted). I don't believe So it's one that can go either way.
With regards to your predicament... kids generally start Uni aged 17/18 here in Qld. So it's not an un-manageable age gap. The subjects you mention I can't imagine her having any issues with those if she did them at GCSE level. They'll be a bit of a step up but not anything drastic.
Key tip would be to remember to look carefully at what the entry requirements are for each course at University when deciding on subjects. It IS very different depending on the University.
Example... IT
QUT - OP: 13, Pre-requisites: nil. Assumed Knowledge: Maths, English (4, sa ...SA means Sound Achievement). Assumed knowledge mean they just assume but don't require you to have either.
UQ - OP: 31, Pre-requisites: Maths B (4, SA), English (4, SA).
See almost the same course with widely different entry requirements... :rolleyes:
So that's just something worth considering.