You are going all over the place with this.
You can't play the Sicilian instead of 1.e4. The Sicilian IS an e4 opening, and occurs when Black responds to 1.e4 with 1...c5.
The questions you should be asking yourself are:
As White, do I want to play 1.e4 or the London System? I can tell you in the learning stages, 1.e4 is better because you get more diverse pawn structures.
Then, as Black, do you want to play the Sicilian or something else (1...e5, French, Caro-Kann) AGAINST 1.e4?
Hi. I am a beginner and I've played 1.e4 for 2 years in the beginning period but not continuously.
Now I'm studying and play London system.
If I want to learn tactics and open games again.
Can I choose to play Sicilian with black to get tactics and open games learning instead of 1.e4 ?
( I will try a few variations of Sicilian.)
Because of playing 1.e4 with white has to meet with many openings : Sicilian, French, Caro Kann, e5 etc.
Or going back to play 1.e4 with white is better for learning?
Thank you.