Which opening should I learn ?

I have been focusing on London for white. And Carol-Kann + Queens Gambit declined for Black

Someone mentioned the Scandinavian.

It's playable.

Below Master level, any opening that hasn't been refuted is playable.

It's not a great opening, but at the 600-1200 level your opening needs are modest.

Just pretend it's secretly a Caro-Kann, dressed up as a Scandinavian to fool people.

In the Classical Caro-Kann opening, White trades his e-Pawn for Black's d-Pawn, and Black's c-Pawn ends up on c6.

Like this (pay attention to the Pawn structure):

In the Scandinavian, White trades his e-Pawn for Black's d-Pawn, and Black's c-Pawn ends up on c6. Like this:

Precisely the same Pawn structure. The Scandinavian is really just a Caro-Kann, but is too cowardly to admit it.

Just play the moves. Whether it’s the KIA or Reti actually depends on Black’s moves. I often see people play 1. e5, sacking a pawn but it is no longer the KIA-it’s now the Reti Opening: Ross Gambit

so in conclusion, it highly depends on your opponent’s choice of move. Nonetheless, I love it

Kings gambit

Yesssss! Totally agree!