Transferring Uni courses

For context, I chose a course that, in hindsight, I should’ve known wouldn’t lead to many job opportunities and has become increasingly competitive. In my current course, it seems like the teachers were trying to prevent students from leaving, as we were never told about the deadline or process for transferring courses.
After speaking with my student advisors and the course leader for the subject I’d like to switch to, I was told that I missed the transfer deadline by a few days and can’t change courses this academic year. I’ve been given two options: either withdraw from my studies or complete this year in my current course and transfer in September 2026.
I wasn’t given much detail, and I’m not very familiar with how university levels work, as no one in my family has been through this process. They mentioned that I could start the new course at level 4 next year, but I’m not sure if level 4 is equivalent to the first year of university — meaning I’d be in uni for four years instead of three.
Would it be possible to move up to the next year with the students currently taking my future course, or would I have to start from the beginning?
The good thing is that I studied this subject for my A-Levels, so I already have a solid foundation and could probably catch up on the second-year content over the summer holidays.