@billsnewhat Your husband sounds unrealistic.
I don't know what his father died of, but at 63 it was likely to be cancer or heart disease. These are both linked - though not solely of course- to lifestyle.
Your DH ought to focus on keeping fit and enjoying life NOW. He may die at 50 or he may live to 101. Who knows.
Neither of you appears to have taken advice on pensions . At your age now, you are likely to have to wait till 70 for the state pension- been talk of retirement age rising to 70 in the not too distanct future. THis means you would rely solely on your personal pensions.
Do you have one? Are you putting money into a pension either through work or your own scheme?
What kind of pension does your DH have now?
What investments is he making?
I've not read all 12 pages but picked up something about your DCs and uni. It's perfectly possible for students to get through uni without parental support- they get a loan for a start, and can also add to this through part time work. We helped our DCs out with living costs , but many of their friends had no parental help. The other thing is, by the time yours are the age for uni, the whole loans or grants system may have changed.
Get an appt with a finance expert on pensions and get real- both of you!