As I understand it couriers don't work on bank holidays, and neither do RM.
So I would expect anything ordered today to not make it into the delivery system until Saturday at the earliest (if RM do a pickup then), or Tuesday most likely, for delivery from Wednesday onwards.
Stuff that entered the delivery system yesterday will probably arrive Saturday (if RM, or couriers if saturday delivery has been chosen/paid for) or more likely Tuesday.
That's at a guess.