(school) if at lunch the teachers let you sit anywhere, ask her if she wants to sit at a different table (prefferably empty) and let her know there.
(TARDIS) lemme know how that works out!
(school) Well then find a good time, like during a passing period, or during lunch. Maybe even ask where she likes to go and meet her there.
(TARDIS) Well if its just you and her in the TARDIS then There yah go!
bring her to a secluded area- dont do it w/ others around.dont hesitate- just tell her. After you tell her, give her some time to think about what you had told her