Once you enter the morph ball tunnel in Sacred Bridge at the beginning of the game, you normally aren't able to return to GFMC Compound until much later in the game - Sacred Bridge requires Dark Visor + Seekers and the other ways require Power Bombs.
You actually CAN get to Sanctuary early if you do the 101% Glitch because the gate doesn't actually appear until after you trigger the cutscene for some arbitrary reason. However, you normally can't actually go anywhere in Sanctuary because of the Boost slot + barrier (and possibly others. It's been a while since I've gone to Sanctuary through the front door) barring your way.