Hi Liz most Birth Death and Marriage records for England Still Exist.During the London Blitz It was Military records that were Destroyed.
The London Archives hold some Records If Irish.
Kew holds most records for England.
Depending on where People live,There are Various online options.Finding People Via Bmd for Various counties.
Electoral Lists Will tell Where Living.
192.com will show some births or deaths but are expensive
cheaper to pay a subscription to Find my past.
For Example if you go to Lancashire BMD on the left of the page it has counties.
Try that.
Mike