going by a name that isn't on my birth certificate at college?

for personal reasons, i don't go by my birth name. my friends and teachers mostly call me by this name, it's the name i use on social media, and i plan to change it by deed poll when i feel in a better position to do so (my parents don't like that i want to change my name and i don't want to change it just yet because it will upset them).

when i start college next year, how will i get people to use my chosen name? should i say something on my application? it's a while away but it's been bothering me lately. thanks in advance for any help.