The dangers, at a circuit that saw two huge crashes involving the dominant Audis last year, will have to be negotiated with care.
The two Britons will join Spaniard Lucas Ordonez in a Greaves Motorsport-run Nissan LMP2 team for the 24-hour sportscar race at the La Sarthe track on June 16/17 with the aim of getting to the finish as best in class.
There have been other father-and-son pairings over the years, with 1992 Formula One champion Nigel Mansell and his sons making a short-lived appearance in 2010, but this will be the first time former F1 racer and commentator Brundle has taken part since 2001.
"We are taking it very seriously as I'm sure Nigel was. You can't play around with Le Mans," he told Reuters in an interview.
"It's a hell of a challenge and we need to get to the end. We've got 18 cars in our class, 56 cars in the race, it's the equivalent of a grand prix season more or less in a day that you do in terms of miles that you are going to cover and it's hard to get to the end of it."
Brundle won Le Mans with Jaguar in 1990, before he became a full-time Formula One driver, and calendar clashes with his other commitments have kept him away in recent years.
He freely admits that there is an element of "the old guilt trip", making up for all the birthday parties missed and parental absences in his years on the road, but mainly it is about racing.
Alex, 21, competed in Formula Two last year and is ultimately aiming to follow his father into Formula One. He will be in GP3 at Formula One's European weekends this year and also the European Le Mans series.
Brundle senior said it would be a strange sensation to be battling in the midfield at Le Mans with the Audis and other LMP1 cars blasting past.
"I have only ever been there in the fastest cars, with the works cars, as team leader," said the 52-year-old, whose last lap at Le Mans was as race leader for Bentley.
"Funnily enough these cars that we are in (now) do about the same lap time as I used to do in the works cars. They are not slow cars, it's just that the Audis are going unbelievably quickly now.
"What I am going to struggle with is that I am not used to anybody catching me at Le Mans and passing me. And apparently the lights on the Audi burn your paint off, they are so bright. And you can't tell whether they are one km behind you or 100 metres behind," added the Briton.
Alex tested at Le Mans last year, with his father on hand to advise him on potential perils.
"Alex's job is probably to help me go faster on a lap-by-lap basis but my job...is to say: 'Here's where it went wrong for me in the past' and: 'Here's some near-misses I had' and: 'Here's how to cope with this situation'," said Brundle senior.
"I suspect it's completely different for the pair of us but for me it will be 'that's my boy', and helping strap him in the car and sending him off down into the night will be something quite amazing.
"Sharing that incredibly intense experience with your son is something pretty amazing...but first and foremost we are there to win the class, we are there with our racing heads on."
Le Mans, he said, was the perfect timing.
"It just fits, father and son. It works for the sponsors, it works for the manufacturer, it gives Alex a starting point in sportscar racing. He's doing the whole championship and it's a window of opportunity for me before I get too old," said Brundle.
"I'll be 53 when I do the race, while I can still just about hang on to his shirt tails speed-wise and get the job done. I won't be a burden to him that's for sure but you don't know how much longer that will be the case for."