I'm struggling to take all mine this year, but then I get 31 days + BHs + 5 days that I opted to "buy". I also get time added on because I don't work on Mondays, which is when most BHs fall.
I also had 5 days carried forward from last year, because I was off sick for 6 weeks following surgery when I only expected to be off for 2 weeks, so the 2 weeks that I'd booked ended up being sick leave, not annual leave.
It's not helped by the attitude to holiday where DP works. He can't have leave at all in April, even though it being the end of the financial year makes no difference to his work whatsoever, and they've just introduced a rule that no more than 3 people from any team can be off at any one time. This means that he can't have the 2 weeks we'd decided to have, even though 3 clerical assistants being off has no impact on the work of the payroll specialists he manages!
Loads of people have left the team I work on (they're all jumping ship before expected 50% funding cuts later in the year), which has made it really hard for me to take leave as the number of people left to cover my caseload is so low. The chances of finding another fortnight we can both take before the schools break up are slim, and we hate going away in school holidays.
In a sense, it's our own fault. Because we go touring in our motorhome, we don't need to book anything, so don't plan in advance. I'd be happy to, but DP is looking for another job, and didn't want to commit himself to time off in case it caused problems with start dates etc. I warned him this might happen, so next year will just put my foot down about it.
I can really see how people end up losing their leave, but I also think that if they've requested leave that hasn't been allowed, they should be allowed to carry it forward (providing that they have used at least the legal minimum).