How to get a referee (International US student)

Hello! I am a US highschool graduate who is interested in going to uni in the good ol UK. I am trying for University of Derby, Loughborough University, University of Nottingham and University of Sheffield (yes I know they aren’t the average aim for a foreigner but my fiancée who lives near those schools and I want to be near her). I have made my UCAS account and have started my application for 2025 school year. I however am lost on the Referee/ Reference section. I do not have any connections inside of UK besides family and my fiancée. What do I have to do to be able to get one. Is there specific requirements? Any advice would help in this matter. Please and thank you!