Don't quote me, but I may be wrong, however...............
I am told that the normal IATA rules apply for handbaggage, whatever you cannot take on a civvy plane applies apparently to military ones to.
There was an argument about this on here about 12/18 months ago but can't be arrsed to find the link, but it boiled down to the fact that if a military aircraft was diverted for whatever reason into a civvy airport then your hand baggage must be to the civy standard, ie must clear civvy security screening in case you have to go through a civvy departure hall.
If it's like LHR currently then PSP would be fine just keep the batteries separate from the device as this will cause a few looks and possibly the rubber glove treatment from some hairy arrsed security type.
Again this could all be b0ll0cks and I am completely wrong.
Stuff like PSPs are fine - stuff like hexi is bad! Electrical / electronic devices are looked at because they could cause a risk to the aircraft - wireless, wifi and Bluetooth are the sort of thing I mean - and mobile phones.
'570mils' is correct. Hand baggage regulations for trooping flights from Brize Norton are exactly the same as if you were flying on Easy Jet to Ibiza. Weight restrictions are different but what you can actually carry on the aircraft is exactly the same.
If you are travelling in uniform and usually have a Leatherman/Gerber on your belt remember to pack it in your hold luggage.
Keep batteries available so that you can show that your electronic devices actually work.
Oh and make sure your batteries aren't service issue green ones as misappropriation of service supplied items is an easy ping for a bored copper.