It's 28 days minimum in the UK[1] (for a full time employee) but these can include the public holidays (8 a year in England/Wales, 9 a year in Scotland and 10 a year in NI).
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In reality most IT companies give ~25 days and give the 8 public holidays off too. Longer service often gets you more days. I'm up to 27 days/year (plus the 8 public holidays).
Any reasonable IT company will also require you to take all of your holiday during the year, it's a manager's responsibility to ensure that his team are using their holiday. There's certainly no pressure to not use all of the days! I can carry over the odd day or two across years but generally not allowed to accrue large amounts of unused paid leave.
We don't have a concept of an allocation of "sick days" either, if you're unwell for a day or a few days you can self certify yourself off work sick. If you're ill for longer than a week the expectation is that you'll provide a letter from a Doctor explaining the absence. If you're ill frequently then the company will discuss it with you (and if you're pulling frequent sickies then that'll be dealt with as a disciplinary). I've had 3 days off sick in the last 5 years.
1. https://www.gov.uk/bank-holidays#england-and-wales