Further training for working with people with disabilities?

I'm 16 years old and will be graduating from high school next year. After graduation, I want to spend a year abroad to complete a voluntary social year (FSJ) and then study social work. I've already found a position I'd like to apply for. It's at a Waldorf institution in Great Britain. I really like the position and I really want to go there. My problem is that I would mainly be working with people with disabilities. Before anyone complains, I don't have problem with disabled people. I lived with my mentally disabled foster brother for 10 years (FAS with care level 3) and have also often had contact with other mentally disabled people in my environment who, for example, have developmental disorders. My problem is that I don't feel qualified to deal with mentally and, above all, physically disabled people. I therefore wanted to ask if anyone knows of any training courses or courses (preferably with a certificate) that I could take in my case. The fact that the courses are certified would be good for my application and to check their reliability. If anyone has any further tips, I'm also very open to them!

(I also recently acquired the Juleica, but it probably won't help me in this case, should I still add it to the application?)