BCP separation question

BCP question, I by no means am out of shape, the Navy personnel at the hospital were laughing their asses off when they saw me roll up with a Body Composition Paper to be signed to say my thyroid is ok. They straight up said, you don’t need to be on this program. I throw around 50 cals easy and I’m a SAW gunner, plus I love the gym and to swim. So here’s my questions.
Assuming i “fail” marine corp standards and get admin seperated, what is the discharge? After 6 months with a job does it change to an honorable discharge? If that is the case, and even if it isn’t will I still get the GI bill?
I only feel the need to explain what I look like because this needs to be a conversation about my questions, not some attack on my physical look because some motards think that Im bsing it to make myself look good online.