LHR depends largely on the time of arrival and what flights arrived before you. If you walk fast and get to border queue first you’ll see how it fills up behind you and that’s where the long wait can begin. Even worst if an A380 landed right before your flight.

I suggest applying for for the Registered Traveller program if you frequent LHR. It allows you to use The EPassport gates.

https://www.gov.uk/registered-traveller