c4 in general, and the Catalan in particular

So I recently switched to playing d4, and I like it a lot. I feel more comfortable playing it than e4. I really like the look of the Catalan for me. My question is I know from the little bit I have studied the Catalan, that you can vary the move order to end up at the same position (one of the reasons I like it). Why in general would you play c4 first, and then specifically in the Catalan? Please be thorough and explain in an understandable way for a player rated under a 1000. Thanks in advance for all responses.

I usually play c4 first to avoid any of the 'nonsense' that flies around after 1. d4, and as a bonus you can avoid most KID-like structures. Don't really have the time to answer more, but you can always question me through chats

The English is very flexible and has transpositional opportunities. 

For example, you get a Reversed Dragon position and have not committed the d pawn yet. Decide between d4 or d3?

D3 = Reversed Dragon

D4 = Catalan

First queens gambit is main line and preffered by super gms so its automatically is first choice at least for me

And catalan is also good opening and also used at super gm level but blind foldly playing it make it same as London system

So i am also both d4 and e4 player and queens gambits and catalan are my two top openings as d4 but i use catalan mainly against the english defense or queens indian /nimzo indian and sometime against slav and kid  it depends on mood. Though I do know all the theory of queens gambit and catalan too play each against everything black throws at me so it offers me more versatility and I can choose one  everytime depending on mood. 

 note: prepare both against every thing black can throw at you and be more versatile then playing catalan as London system 

#1
The #1 reason to prefer 1 c4 over 1 d4 is to avoid the Grünfeld Indian Defence
1 d4 Nf6 2 c4 g6 3 Nc3 d5. Indeed 1 c4 Nf6 2 Nc3 g6 3 e4 forces black into a King's Indian Defence.

The reason for 2.c4 is that the Catalan is not a catch-all system.

The Catalan relies on Black's DSB getting blocked by his pawn.  This is specifically why the Catalan is reached via 1.d4 Nf6 2.c4 e6 3.g3 d5 4.Bg2 OR 1.d4 d5 2.c4 e6 3.Nf3 (this should be played first to avoid the Dutch - if 3...f5 here, White gets a superior stonewall with Bf4, e3, and Bd3) 3...Nf6 4.g3.

The Catalan is a great way to fight the QGD or attempts at the Nimzo.

But 1.d4 d5 2.g3 is inferior.  Black develops his LSQ OUTSIDE the pawn chain and Black is fully equal, if not slightly better in most lines.