Weasley Mum - Yeah, you could use 'hanging out' as Sarah says. I'm pretty sure I used it in late eighties and nineties but that was largely due to the influence of such seminal shows as Beverley Hills 90210 - I'm not sure the Marauders or Trio Era would use it as they don't watch such classics :p
Molly - Hmm, adding to the ones Northumbrian and Sarah said, I'd also mention specific ones from my neck of the woods (London) like 'honey' 'angel' 'flower' 'petal' 'sweetheart' or anything that takes the girls name and makes it sound sweeter. For instance if a child can't say its name properly when they're two they'll often get called that for ages. My daughter couldn't say the name Jessica so is often called 'Jecca'.