I am going to be the Party Pooper, here. I am a similar age, but did medicine straight from school.
I am not sure what you are hoping to gain from going to med school at nearly 50? This is a genuine question as there are lots of fulfilling careers that don't need the sacrifices, long hours and lack of autonomy you will have for YEARS if you do this.
I cannot imagine restarting again now - the energy needed, the being bottom of the pile and GENUINELY having no idea what you are doing with all the anxiety and discomfort that brings, the disruption to life in terms of having to move for junior doctor jobs, work shifts, long hours.
I have no doubt you could do it, but would question why anybody would want to, given the impact it will have on your life, family, friends etc.
You will be 54/55 by the time you qualify, (even 53 if GEM is going to be tough) you have 2 years of long shifts, moving jobs, but worse than that having essentially no knowledge of what you are doing in terms of actual medicine. Then, even if you go into General practice, which is the shortest qualification route, you have 3 years of again changing jobs every few months, being the lowest in the pile with all the anxiety you will have because in each specialty you will again have no idea of what is needed, let alone the way the ward, team, etc work.
If you sail all through this, you will be a minimum of 58 by the time you can work as a GP. And then it becomes really scary, as you are on your own, no boss to ask about things you are uncertain of and although you will have colleagues, they will be too busy to respond immediately to all your queries.
Plus the hours at this stage are still 8-8, and this interferes with all the normal things you want to be doing at this stage in life (I rarely make my book club, do not do the classes and fun evening things I would like to, miss events with my friends and this is when my Partner and I bend over backwards to try and find a good work/life balance and cancel.swap/change things where we can).
I would say it takes 2-4 years to become confident in what you are doing, to not have an underlying feeling of fear at what somebody is bringing you through the door, and by then you are at least 60, and trust me, I can only work part-time now, and in 10 years time expect to be retired!! Plus if you are working LTFT then it takes longer to develop that confidence, comfort and enjoyment of your job (or to actually qualify if you do this straight out of Foundation Years).
I would be looking at a Physician's Assistant if I were in your position. Shorter training, still opportunities to develop your career and in Primary Care they are going to be doing pretty much the same job in a few years, with regular hours, defined protocols to work to and as much (or little) responsibility as you want, whilst still getting a pretty good salary. Or a paramedic (but would not want the shifts).
Whatever you decide, I take my hat off to you and wish you luck. Please DM me if you have any questions you don't want to post on here