Advice on ab initio languages

I'm a yr 12 student hoping to apply for french and then ab initio Spanish or Italian at Cambridge. I haven't been able to find much information on how much reading they look for for ab initio. Like in my personal statement should I be discussing both languages, or just french, which I am doing for A-level?
Thanks all!

You would be expected to discuss and read texts from and/or about both languages. Especially for ab initio, it completely acceptable (and expected) that you do this in translation.