Karise: have you talked to current parents to find out what kind of work their children do? If not, you could get a parent's number via the school office, or could ask the secretary to pass your number on. Parents are the best sources of information about particular schools!
You also need to visit the school, preferably on a normal day rather than an open day (though I'd do both). The work on the walls, in the children's books and so on will give you an idea of the expected standard. Teachers should be happy to show you the children's work; if not, I would give the school a miss!
Don't worry about extra-curricular stuff. My children's prep school has loads of children who play every instrument under the sun and are national junior tennis champions; it also has lots of people like us who do stuff all outside of school.
If it's an academically selective school, find out how they assess the children and practise that with your daughter. If it's not academically selective, she will be fine if she's bright and enthusiastic. She probably will be behind in some things - but it's a marathon, not a sprint: they will all end up at pretty much the same place!
Generally, it sounds as if your daughter would do well. You'd be likely to find that most Y2s are at least the 'average' Y4 standard in reading, and possibly a bit beyond (as they are at my DC's non-selective prep - my DS is in Y2) - so she would have lots to do, and wouldn't have to worry about being bored. Good luck!