I've never known anyone to get a higher education place studying music without having achieved Grade 8 (which is the highest possible grade) in the Royal School of Music's examinations. I simply can't see you being offered a place to study music. Similarly, it's unlikely that you'd be accepted onto a Master's course in music without having achieved at least a 2.1 Bachelor's degree in the subject first.
The Prospects website exists to guide graduates in their career choices but it's well worth looking at even before you get to uni (and, indeed, even before you've decided on what you want to study). For example, the types of jobs which can often be available to photography graduates are shown here:
https://www.prospects.ac.uk/careers-advice/what-can-i-do-with-my-degree/photography
Here are the equivalent links for film production
https://www.prospects.ac.uk/careers-advice/what-can-i-do-with-my-degree/film-production
and film studies
https://www.prospects.ac.uk/careers-advice/what-can-i-do-with-my-degree/film-studies
It's well worth exploring the Prospects site further, as it's full of useful information and advice.
https://www.prospects.ac.uk/
There's nothing to prevent you studying for a second Bachelor's degree after gaining your first one except for the big problem of finance. (You wouldn't be able to get a student loan for such studies). The 'Postgraduate' section of the Prospects site can guide you further.