Nah the head of 6th form or form tutor (or someone) will normally have to add their own little shitzo to the UCAS forum where they talk about your general persona. Kinda like a reference on a job application.
And, although it's not the biggest deciding factor for the admissions tutors, I'd say they may frown upon it slightly. Why should they accept someone who doesn't bother with punctuality (and thus may not bother with all lectures, classes, seminars...) when they can accept someone who wears Big Ben on his/her wrist. I'm not having a go or anything, of course, because it's not my place to do so. I'm saying though, it might put a downer on your application depending on the type of person your admissions tutors turn out to be. They won't accept someone who won't make full use of their facilities, and stuff... if you get me.
So yeah, won't matter that much... but if you can slip your tutor some sexual favours to deter him/her from putting that on, then definitely do so.