You will get issued your CBA (Your standard regulat combat body armour) in the UK, and on arrival in to theatre your should get issued with Osprey. There is an embargo on Osprey leaving theatre and you fly in and out in your own armour - basically there isn't enough to risk losing it in the stores chain in the UK. Also, although its heavy, Osprey is the dogs danglies - it will stop 7.62 armour piercing rounds.
FYI Have just had a future kit demo for ops kit that is planned to roll out in 2011. The Ospery is being modified and I asked about Dragon Skin. They told me that due to its disc like make up, although great for direct impacts if a round strikes it at an angle its about as good as tissue paper.
They informed me that an American solider was shot and killed whilst wearing it and now the family are taking legal proceedings against the manufacturer. The round struck under a disc as the bloke wearing it was lying down. The new Ospery looks great and its ten times easier to move about in it!