[clu]

As said before everyone is entitled to four weeks holiday, unfortunetly different companies deal with this in different ways, at my work we close for four weeks, in two week blocks, but that is made clear before to potential staff. Some companies also include bank holidays in the four weeks which is a bit tight. Your holiday entitlement should be stated in your terms and conditions and then contract.

If i was you I would ask for a copy of their policy on holiday requests, surely it would be reasonable to find out in a stated amount of time instead of waiting until the rota comes out.
Just keep asking for it in writing it will probably annoy them but at least you will know how the decisions are made.