While it's theoretically possible to transfer from one medical school to another, the specific circumstances you've mentioned present significant challenges:

The structure and content of medical education in India (especially in prestigious institutions like GMCs and AIIMS) often differ significantly from those in the US and UK. This makes credit transfer and curriculum alignment extremely difficult.

US and UK medical schools have highly competitive admissions processes, often requiring specific pre-medical coursework, MCAT or UKCAT scores, and extensive extracurricular activities. It's unlikely that your first-year MBBS coursework will fully meet these requirements.

The second option is viable. You can start preparing for MCAT and UKCAT and appear for the exams next year. In the interview round, you can even brag about having experience in the Indian Education System in the field of Medicine.

Hope this helps