Asked to give a talk about uni life - help?

I'd impress on them that university is what you make of it and that your experience can be wildly different even to others on your course.

I'd start with asking whether uni is right for them, so whether they can get interested in the subject (e.g. liking maths and physics is one thing, liking engineering is another) and discussing alternatives, giving them some ideas on how to figure out which uni is best for them like looking at social life, what they want to get out of it, etc, showing sometimes stats do matter. Show how experiences can vary, some people will grow, some will push through it and others won't handle it.

Encourage some kind of experience being more independent beforehand, focusing on travel, budgeting, shopping and cooking, learning and generally starting new things. Very much emphasise the independence of being at uni, it's a huge part of the experience.