Hey there,
As said above you don't necessarily need work experience to access a place on your undergrad, but it will benefit your CV moving forwards into the future.
The recommendations you've been given already are a great start, although I imagine a lot of places will ask that you're 18. If you are then great, finding a position such as an LSA or working with clients in a care home will give you great skills and a chance to earn a bit of money alongside college/uni too. I know a lot of fellow students who do this. Mental health charities are normally looking for volunteers too - I'm currently doing this during university and the experience i've gained so far is invaluable and will really help me develop my career when I graduate!
If you're able too, I would see if your careers office/teachers can help you find work placements/opportunities as sometimes they'll have a clearer idea of what will help and who will take you on. I'd say anything where your supporting another person 1-1 is a great start. Even customer facing roles are good for developing your skills as you usually have to talk to all sorts of people, think on your feet and work under pressure.
Do try to enjoy your time in the run up to uni though!
I hope this helps and feel free to ask me any questions,
Lauren -Official Student Rep