If staff can take the leave they want when they want then it is clear that the organisation is over staffed. Most well staffed companies rely on points systems or frist come first served or if you get xx perid this year you can not bid for it next year etc.
No that is why we have a
Leave Roster. You know..the book or planner that you put down just what leave you want. Other people do the same...and all the leave allocations are filled [mostly amicably].
You are then entitled to that leave. At least that is how it works at MACC and Manch Tower/APC [and
AFAIK the rest of the CAA too]
Using computers at work for non-work related issues such as PPRuNe is never going to go down well with management. Every IT policy has the old "use for work related matters only" and I can't see calling people "a piece of sh1t" being a good example of how a company's staff should deal with their customers whatever the reason.
We are allowed to use our PCs for "none work related matters" in our off duty time.
Provided that we don't abuse the system 
watpiktch