London when black plays e5?

You don't play the same moves every game totally irrespective of what the opponent does, if that's what you're asking. Not even in the London.
You need help that goes beyond what anyone on this site can provide, I'd recommend watching some beginner videos (find them on youtube). Make sure they're very beginner or they might still confuse you.

3...e5 and 4...Bg4 are both blunders. You win a piece after 4...Bg4??
5.Bxf6!! - REMOVAL OF THE GUARD!
If 5...Bxd1, then 6.Bxd8. Both bishops are hanging. If he takes yours, you take his. If he retreats, you retreat. You won a Knight.
If 5...Qd7, guarding the Bishop, the 6.f3! You attack his piece with your pawn just like he attacks yours. If he takes your bishop, you take his, and again, you won a Knight!
If he plays 5...Qxf6 or 5...gxf6, you play 6.Qxg4, and again, you won a piece!

3...e5 and 4...Bg4 are both blunders. You win a piece after 4...Bg4??
5.Bxf6!! - REMOVAL OF THE GUARD!
If 5...Bxd1, then 6.Bxd8. Both bishops are hanging. If he takes yours, you take his. If he retreats, you retreat. You won a Knight.
If 5...Qd7, guarding the Bishop, the 6.f3! You attack his piece with your pawn just like he attacks yours. If he takes your bishop, you take his, and again, you won a Knight!
If he plays 5...Qxf6 or 5...gxf6, you play 6.Qxg4, and again, you won a piece!
Real

3...e5 just blunders a pawn, and 4...Bg4 just blunders a piece in a very straightforward way.
Instead of trying to "learn this London opening" you'd rather practice tactics for the foreseeable future. Everybody can blunder something, at any playing level, but if you miss such trivial things then you shouldn't bother at all about opening theory.