It isn't unrealistic at all, op. I helped a bf look into this a couple of years ago.
He eventually decided not to pursue because he couldn't financially sustain himself during training, but as another pp said if you can then it is very possible.
Just don't underestimate how much £ you'll need - study materials, petrol/public transport/food plus any exam fees pre and post uni or extra tuition to get you up to speed. Do a really intensive cost breakdown.
The other big thing for your application will be work experience which is difficult to get at the best of times. Think outside the box. Email a consultant or nurse you know and ask directly if you can't get through the hospital/ practice work experience application route.
Look at any volunteering roles remotely related to the medical fields.
Lots of YouTube videos of operations etc. Lots of documentaries on BBC and Channel 4 about life as a doctor.
Reach out to doctors and ask about their training experiences. The hours are long and anti social until you are established so you have to be sure you can do this without it affecting your family life too much. You'll need support.
There are less than a dozen unis that offer graduate schemes and fewer which admit students with non science backgrounds unless they do a foundation degree first. Make a table of what the various options are and what their admissions requirements are.
You might need to study intensively to pass the entrance exams, especially if it's been a while since you did them but there is specialised tuition support out there if you can afford it.
Research, research, research and good luck!