word document batching

I have a word document posted to me daily by email. It is anything up to 300 pages long. I need a macro to batch it into multiples of 6 and give each batch a number which needs to be added as a header or footer. I would also like to specify the commencing batch number so that I can carry on a sequence throughout the week.

A lot to ask? Maybe and I'm sorry but I don't know where to start. Any ideas or staring points would be really appreciated.