That is definitely a hefty workload!
The upside is that the Conservatoire route is very different from the University one, so you don't need to make one personal statement work for both.
One thing I would advise is booking all the open days for the conservatoires this year. The application form is due back on the 2nd Oct for 2026 entry, so 27 entry likely to be some similarly early date, and open days in the Autumn are AFTER the closing date, so you need to have everything sussed in Y12 rather than Y13.
In my wanderings round Music degrees, there are quite a lot of dual major ones, but they tend to be more academic less performance based and at RGs rather than conservatoires. I didn't look in depth as DD definitely only interested in very performance heavy courses, but was intrigued how many options there were.
I wish you luck on the uniform front!
DD's college have no rules at all, so I guess I will be having more than a few 'you are not leaving the house in that' conversations this year. DD did seem to manage to live permanently in PE kit (baggy joggers and a sweatshirt) for last 3 years of secondary as it was permitted on PE days or if you had after-school sports, so I have suggested that she just continue in the same vein...