I agree with much of what has been said so far. Its the way the rules differ everywhere you go that is the main annoying point.
Here is a positive and constructive suggestion.
The DfT (or whoever is responsible for airport security these days) should draw up a nice A4 booklet which lists the specific requirements for security checks. As in, what you can take, what you can't. What bags you can use, what you can't. Whether you should have to take your shoes and belt off every time. Or not. This document should be distributed to all CAA professional licence holders and cabin crew (or airport ID holders) and also to every UK airport authority, where it should be available at every security point as the National Airport Security Guidelines for Crew Security Checks. This way, everyone knows the rules, they are used in the same way at every UK airport and anyone (security or crew) trying to get round the rules can see what the rules are in black and white.
I agree that it is stressful and time consuming to go through security these days, particularly if away for a few days and taking hand luggage through security with you. It seems that if you have your little plastic bag correct then your suitcase won't get searched, so you put whatever else you like in there
Of course, that would be completely against all security requirements and I would never flout the rules in that way.
Also, for pilots, come on guys, there is a time in every flight where there is only one pilot on the flight deck, we all know it ain't difficult to fly the thing into the ground if you really wanted to - you wouldn't need the help of an extra 50ml of toothpaste.....
The most ridiculous thing of this whole scenario is that down route you don't get anything like the same check. So you arrive, leave the aircraft, pop into the terminal, buy whatever you like, return to your aircraft with oooh, maybe 200ml of toothpaste (whatever next!!!). And no one knows or cares.
In Greece for example, it is possible to go through security with barely a glance, carrying whatever you like (and yes, this is wrong too). This does make crew a bit weary when it comes to dealing with UK security.