No I've not heard of any such schemes - and medical schools may have concerns about someone who did not complete a dentistry course in a similar way that people who start but don't complete a medical degree are generally not permitted to be admitted to any other medical degree in the UK.
I'd suggest contacting any medical schools you may be considering applying to in order to understand if they would consider such an application before making any major decisions. Note also as you've missed the October 15th deadline for applying to medicine this year you would need to apply next year, to start in 2026.
There are a number of graduate entry medicine courses that have specific accelerated routes for dental graduates (although these are aimed at those planning to become oral and maxillofacial surgeons as I understand and more competitive than the standard GEM courses).
If you are asking this as someone who hasn't yet started a dentistry course but decided you prefer medicine (but hold a dentistry offer), I would strongly suggest not taking up a dentistry place and taking a gap year to apply for medicine, to avoid any potential issues.