Boys Beware by Jean Ure
Another brilliant story containing comedy, calamity and cool characters by acclaimed writer Jean Ure.
Even though Tash and Emily go to a nunnery (well, an all girls' school, which amounts to the same thing!), they are into boys in a BIG WAY. They're also stepsisters and the hugest of best friends. So when their mum and dad have to go Peru for work for a couple of months, leaving the girls in their own flat in Aunty Jay's house, they are seriously excited.
Of course they've got to take their weird elder sister, Ali, hundreds of her Star Trek videos and Fat Man the cat, but apart from that they are INDEPENDENT GIRLS. And when they find out that there's a dishy boy living in the flat downstairs, they just can't believe their luck...