0.7mm is quite thin, you would be about there with one layer of 200gsm and one layer of 450gsm carbon. That would give you a thickness of around 0.65mm, so you could go a bit stiffer by using a 650g layer instead of the 450g to give you a thickness of roughly 0.85mm. Sort of depends what strength you need from those panels. Not sure what weight bi-axial you are thinking of using, but I suspect your layup would be substantially thicker than the 0.7mm you are aiming for. 

Hi Hanaldo thanks for the reply. 

Want do you want these panels to be? Lighter than the ali, stronger than the ali, same as the ali? 

I'd be looking at having a similar,  if not slightly better strength than the ali.