So much for (something)

"So much for ___" is something that you say when you're giving up. You've realized that you won't be able to do what you wanted to do. The most common use of "So much for ___" is this:

So much for that idea!

You say "So much for that idea" when you're trying to solve a problem, and you've tried one solution to the problem but it didn't work.

The other way that "So much for ___" works is by adding a gerund afterward:

It's already ten thirty? So much for getting an early start!

Oh no! He saw us? So much for keeping it a surprise.

All right

This is an expression that people use near the end of a conversation. For example, if you're visiting someone and you think that it's time for you to leave, you can say:

All right, well I guess I should be going.

"All right" can be said in response to something that another person says. For example:

A: Guys, let's call it a day.

B: All right, we'll pick it back up in the morning.

But you can also say "all right" on its own to show that you're ready to end the conversation, even if no one else has said anything.