Right now I would focus on getting onto an undergrad course and working as hard as you can to make sure you get a first or 2:1. You could also look at getting some experience alongside your degree such as working as a HCA or support worker to get that direct contact with individuals in a clinical setting. Volunteering on helplines is also a great way to learn a lot of skills which you’ll use as a psychologist too.
The path to becoming a psychologist is always going to be a long one which requires a lot of patience and dedication. After graduating, most would then do a masters whilst getting more experience, ideally as assistant psychologists or research assistants. Although the application can say that you need a years experience, this is a minimum and many people applying will have several years experience plus additional qualifications, so you need to make yourself stand out as much as you can. Understanding the expectations now will give you an advantage.