i think there will be no problem boarding with that (there may well have been with the carry on suitcase too) but there is a strong possibility of your garment bag indeed needing to be accommodated in some overhead and that may not be ideal. Bear in mind that wardrobe space is slowly being with sacrifices with NEO aircraft’s. Also MAN flights tend to be packed and overhead space quickly crowded though Sunday morning from man is indeed not the worst time. I guess if it has been me, I’d have deemed putting those in a suitcase a lot easier and safer.