As I've been at the same place for a while I've gained extra 4 loyalty days (I think that's the max we get), so officially I get 25 + Bank Holidays + Christmas to New Years.
In addition to the regular annual leave allowance, in my team we can get pretty much as much leave as we'd like since we work on flexible time instead of getting paid for overtime. With that system, if I do an extra half hour each day then I could take a day off every 16 days.
We're also allowed to stockpile the time credit to 24 hours which means we could potentially save up to get 3 days off every other month... luckily nobody abuses the system, otherwise it'd probably get taken away.