Final year Cardiff Uni student here!
All years matter in terms of building a foundation of knowledge and building a relationship with your peers and lectures as well as building academic skills. However, depending on your course, the first year may not be counted towards your final grade. You will have time to adjust but it's important to use this as an opportunity to improve as much as possible before your grades do contribute towards your final grades. In addition, you still need the pass the year to proceed.
All the best,
Jaz - Cardiff student rep