Am I missing something? There can't be that few divorces in the UK?
There are 65 million citizens, so that's roughly 20 million couples I guess. About half of these (10 million) end up in a divorce. If these 10 million divorces happen during a period of 50 years, that's 200 000 divorces every year. So there have been about 150 000 in 2018 already. 5% of 150 000 is 7500, not 200.
Not every couple gets married though, so even if there are 20m couples not all of them would even be married couples (neither of my parents or any of their siblings have ever been married for example).
Plus any 50% divorce statistics I assume would be based on the current divorce rate, while the 65m population figure would include people from previous generations which seem to have had (and continue to have) much lower divroce rates.