If I'm in similar situation, how long can I be away from UK after those 5 days that they'll ask me to stay? Can I be away for let say 3 months or more?

I'm still new here so I can't give you any information about your concern.:oops: But for the meantime let me just share an interesting article with you guys. I read it awhile ago and I find it informative that's why I'm sharing it here. Here's the article: Fewer teens getting early driver's licenses