Applying for Military College for CMT role, how strict are fitness requiremwnts?

Me (17) is applying for a military college so I can later on go into becoming a CMT. I have good GCSEs, great teamwork (I’d say so), good cognition, and medical history. But fitness is my problem.

I’ve always been big and had a negative mindset, but I’ve been doing sports for a lot of my life. I’m overweight with a BMI of 25.2. I can deadlift and maybe throw a medicine ball but I’m dreading the 2km run. I started training and running in December and I had around 7 mins and 20 seconds per km on my first. Now, I can do like 7 mins per km. I need around 4 mins and 30 seconds. And the whole time, I’ve had a bad mindset, I’ll admit.

I’ve told all my friends I was moving and have given up on my A levels since I believed I would quit midway. Now, I’m getting more doubtful as the date of the assesment comes sooner. I want to be a CMT more than anything, but now I’m worried I can’t even become a musician with how bad I am at running. My panic and anxiety is making it hard to keep focus day-to-day and it’s all I can think about it because it matters so much. My assesment is in roughly three weeks, and I wholeheartedly believe no matter what I do I’ll never make that time.

If I don’t get into the military college because of my fitness, what else can I do and does anyone have ways to help me prepare?