The latest paid leaver scheme is (for me with 32+ years) one years money
Still a decent pension too, should be able to go in about 4 years with a £100k lump sum and £18k/year (I've been putting extra into it for a while to boost it)
He would have got the best package they offered (as technology advances meant they needed to shed 000's of engineers). If I recall right it was 2 years money plus 6.66 years added to pension and the ability to take the pension at 50 without an actuarial reduction. Anyone with 30+ years service...
Don't think in terms of "when" but about "how much".
Work out how much you need/want to live on. Consider how much savings you are going to need.
Once you have those figures, then you can work out how long it will take you to get there.