I think they're referring to the offence "Death by dangerous driving" and it now can carry a life sentence[1], but you would really have to be doing something exceptionally bad to get a life sentence - it would have to be deliberate, likely a repeat offence, and have other aggravating factors for that sentence. Real sentencing in the UK is very lenient- famously an American woman killed a teenage motorcyclist when she was driving on the wrong side of the road, claimed diplomatic immunity and fled the country, she eventually returned to the UK to be sentenced to... 8 months in prison suspended sentence.

[1]:https://www.sentencingcouncil.org.uk/offences/crown-court/it...