No, you do not need to go through your school to apply to UCAS. You can simply apply independently rather than through a school.
At some point during your application, it will ask whether you are applying from a school or independently. Make sure you click independently otherwise, it will then ask for your personal statement number; which you won't have as you are not coming from a school/college.
However, you may need an academic reference so bear in mind you might have to get in contact with one of your teachers so that they can provide a reference for you.
If you are still unsure then it is definitely worth getting in contact with UCAS or just browsing through their frequently asked questions.
No, you do not need to go through your school to apply to UCAS. You can simply apply independently rather than through a school.
At some point during your application, it will ask whether you are applying from a school or independently. Make sure you click independently otherwise, it will then ask for your personal statement number; which you won't have as you are not coming from a school/college.
However, you may need an academic reference so bear in mind you might have to get in contact with one of your teachers so that they can provide a reference for you.
If you are still unsure then it is definitely worth getting in contact with UCAS or just browsing through their frequently asked questions.