I would also talk to the coach in advance if that makes sense.
Because in judo you train in physical contact with others, so it’s questionable whether someone who can only rarely be there and therefore progresses much more slowly is a suitable training partner.
But it probably depends on the group and how intensively and quickly the teacher teaches, i.e. whether it is an easy course or whether you want it to progress quickly.
And you have to be aware that you pay for many hours for free if it’s a fixed course and not a block of ten.
