hey, the best way to prepare for the how science works aspect of the day is to look at the key stage 3 and 4 curriculum as each of those outlines how you incorprate "how science works" into teachings.
basically "how science works" is a concept that promotes practical work, experiements, data interpretation, analysis etc (things involved with gathering evidence).
in December when i had my interview this part of the day took place as a discussion, not a presentation, so the interviewer was prompting us to discuss as a group the pros and cons of "how science works"
hope this helps...and dont worry about it, the lecturers etc are really nice and not intimidating at all!
good luck!