Unauthorised term time absence!

Hi there! I'm an 18 year old in year 12, studying in Norfolk (spent a year studying at a different college before returning to my original sixth form so am a year behind my peers) and I'm looking for advice with regards to taking an unauthorised holiday in term time. I'm fully aware of the correlation between attendance and performance so please, I'm not looking for anyone to explain that further! All this is, is a question regarding the legality of my holiday. As I'm 18, I'm pass school leaver age? And because of this, laws regarding fixed penalties notices only apply to children age 4-16? My concern is primarily that I don't want my parents to be served any notices or penalties because of my actions. Any advice? Should I write a letter explaining my absence a week before or just tell my sixth form on the day of leaving?
Thanks!
P.S again, I'm not asking for peoples opinions on if I should have the holiday or not, its a once in a lifetime opportunity. I'm simply asking about the laws regarding the topic and how to approach telling my sixth form.

Hi there! I'm an 18 year old in year 12, studying in Norfolk (spent a year studying at a different college before returning to my original sixth form so am a year behind my peers) and I'm looking for advice with regards to taking an unauthorised holiday in term time. I'm fully aware of the correlation between attendance and performance so please, I'm not looking for anyone to explain that further! All this is, is a question regarding the legality of my holiday. As I'm 18, I'm pass school leaver age? And because of this, laws regarding fixed penalties notices only apply to children age 4-16? My concern is primarily that I don't want my parents to be served any notices or penalties because of my actions. Any advice? Should I write a letter explaining my absence a week before or just tell my sixth form on the day of leaving?
Thanks!
P.S again, I'm not asking for peoples opinions on if I should have the holiday or not, its a once in a lifetime opportunity. I'm simply asking about the laws regarding the topic and how to approach telling my sixth form.