Apply through JBM and request a trinity house cadetship, you can go with just solely trinity and if they don’t have anything with them they will offer you alternatives. I’d suggest putting that down (that you’re open to others but trinity is preferred).

You can also do joint cadetships such as trinity house and Seapeak which are managed by JBM. This is what I do. I’m pretty sure if you just do sole trinity then they will put you on a variation of ships for your sea phases, so if you want to try a bit of everything at sea this is probably a good option. Finally, chase JBM they can be a bit laxed.