Giving good news:

I’m really pleased to tell you…

I’ve got a bit of good news to tell you…

I’ve got some news for you…

I’ve got some brilliant news for you…

I’ve got some great news for you…

I’ve got some wonderful news for you…

I’ve got some splendid news for you…

You know what! I’ve got a bit of great news for you…

Guess what!

Hey! Have you heard that…?

Believe or not…

Reacting to good news:

Wow! That sounds exciting!

Wow! That’s amazing!

You’re kidding! (Oh my gosh!)

Congratulations on your good news.

I’m really happy/excited for you!

Good for you!

How marvellous!

I’m delighted to hear that.

Good job!

That’s terrific, fantastic /superb / incredible!

Are you joking?

Sounds great! Are you excited?

Lucky you!

Oh, how wonderful!