Thanks to everyone for their help. Spent more time on reviews and went back down to the camerashop.
Choice was a D5200 at around £800 including 18-55VR kit lens or the D5100 with the 16-85VR for a total of £820 minus £105 cashback - so final total of £715.
The glass is more important than the few extra features for the 5200. So, went with the 5100. This way I can use the 5100 for a while and if I decide that I want the 5200 later then it should have come down in price quite a bit - at the moment it is just too much extra cash.
The amazing thing is the D5100 body with cashback came in at just £295 from my local camerashop. I am amazed that I can get that much camera for such a small amount of money and support my local economy.
They did also put out a second hand D3X on display whilst I was there for £2399 - if I get serious feature envy then I could go to that and employ someone to carry it for me