Slightly longer version: doing a music degree you have a genuine interest in and will equip you with marketable skills for life is not a bad thing. This is where your experience is, this is what you know and this is what you're good at. It doesn't sound like a random degree, it sounds like one you wanted to do. It could be a good option for you and I very much doubt that it would be a random choice.
I'd encourage you to really think about what your motivation is. Did you read something? See something on TV? Have a really positive experience with the health service? All of the above? What did you do next? What have you done to develop and explore your interest? Have you done the work that allows you to reflect if you'd be a good match for this career? Do you think you have the skills and qualities required for a doctor and can you evidence this? What provision are you making to ensure that you get those A level grades in sciences? How are you going to afford to do them? Were sciences disproportionately affected in your GCSEs compared to your other subjects? If so, what is your plan for closing the gap?
These are the questions that you need to ask yourself and find answers to before embarking on a very uncertain educational pathway that could leave you a year down the line with no further options than you currently have. Take the worst case scenario: say you do your two science A levels and you didn't get the grades you needed. This would put you a year behind your peers. You take another year to resit, it still doesn't go well. You're now two years behind your peers and still at least 3 years away from getting a degree, if that is what you want. What would be your plan then? How far would you take it to do medicine? How much time of your early adulthood would you be willing to dedicate to the process of trying to get in? Is it all or nothing or is there a point where you draw a line and move on to something where you get to experience success and professional development and move on with your career? Again, questions and conversations to have with yourself. What would plans B, C and D look like?
I'd encourage you to look at alternatives to medicine that may be accessible to you already, that might be a better fit, and may be a better platform for getting into medicine later if you chose to do it down the line. Medicine is so visible and high profile (alongside nursing) that I do wonder if you've even considered alternatives to that doctor-nurse binary. A music and language interest would be a great base for professions such as Speech and Language Therapy or Occupational Therapy. These degrees would allow you to have a clinical role on graduating and may play more to your strengths as a person right now.
This isn't a reflection or a judgement on you. Remember, I only have what you have said to go on. But as you're not coming at medicine from the standard two sciences + another subject background, given that you're coming to this later than many (though certainly not all) school leavers come to the process, you will need a plan and you will have to contend with things that a traditional applicant would not have to. And I mean a really practical plan. Remember, taking A levels privately, sitting entrance tests and accounting for resits could end up costing you between £3k and £5k minimum (I've done it just for one A level and I can't personally think of a way I could have done the bare minimum that I needed to do more cheaply). It is also at least a year and likely two years of your life as the majority of people applying to medicine don't get in first time. In the grand scheme of things, maybe it's not much and it becomes trivial in time if it's what you really want but you will need a practical way to accomplish all of that.