I'll try and keep this brief as leave/Carmen etc are all quite complicated and new joiners will get to sit down and really study the systems and how best to make them work for themselves.
So to try and get a weekend off in Summer there are various options, the easiest is Gold days. A full time pilot on the 73/75/76 has ten of these and they are booked on pairs up to a year in advance down to about 2 months.
Then there is Silver days, there are again 10, booked on pairs available about 3 months out down to 2 months.
Another option is leave, now this is the most complicated bit that only the dedicated understand (I don't) we have a points based system essentially the earlier you book (around a year) and the closer to high season (August) then the higher the points. The higher your points the less likely you will get your requests in the following year. Only a small amount of small blocks can be booked per season. This is to protect the roster as the odd day here and there would really cock up the rostering system whereas the standard week won't.
The final option is Carmen, this is our rostering preference system but most find trying to get a specific day or weekend off iffy at best. I put in for every weekend off in Carmen and get two or so a month so I'm happy.
The happiest and most successful people know the systems well and put a little time in to organise their lives, I find those who only try for August off every year and never really bid through Carmen or use GDOs/SDOs are those that complain that the systems don't work.
Just to add an example, I put a bit of time (an afternoon a month) into organising my life and next year I have a week in March for skiing, GDOs April for a wedding, two weeks in May for golf and another foreign wedding, GDOs in June for my birthday and GDOs in August for the bank holiday. I'll get a week in September as well. The only moth I haven't covered is July so I'll book a weekend off now to make sure I have at least one.
Hope that helps, DC