is it the bath or waste that doesn't have a hole if it's the waste then u either need a combined bath waste & overflow or a pop up waste which would have the overflow built in, sometimes u can buy a click clack type plug that u push down to seal then push again to release if u have one of these it might not have a hole 4 an overflow in which case i would suggest that u get a plumber involved as he may need to fit parts from a combined waste to it to get it 2 work, i've been in the plumbing & heating industry in southampton since 1982 & i haven't seen a bath without a hole 4 a overflow.
Hope this helps.
Keith Gillyon Plumbing, Heating & Building Services., May 2009