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It's sensible to put savings away
You have to be careful though - if you are putting away large amounts of cash savings for retirement you should have first
- maxed out your pension allowance (somewhat age depending)
- maxed out your S&S ISA allowance
- paid off any expensive debt
What you describe is for people who are so rich they just don't know what to do with their money, and are happy for their capital to be munched by inflation (unless you were assuming it was backed by S&S, in which case your return is guaranteed, but in all probability it will be better than what you'd get with a cash savings in interest rate.)
- maxed out your pension allowance (somewhat age depending)
Lifetime ISA is pretty non-standard to be fair, but yes, as some kind of not-quite-pension like thing it's interesting.
Instant-ish access stocks and shares ISAs like nutmeg are what you want but you need to have been feeding them for the last fifteen years