1. ‘The best of both worlds’ – means you can enjoy two different opportunities at the same time.
“By working part-time and looking after her kids two days a week she managed to get the best of both worlds.”
2. ‘Speak of the devil’ – this means that the person you’re just talking about actually turns up at that moment.
“Hi Tom, speak of the devil, I was just telling Sara about your new car.”
3. ‘See eye to eye’ – this means agreeing with someone.
“They finally saw eye to eye on the business deal.”