Strategy review please

MartialArtMan

I'm 43 and still have 21 years left to pay on my mortgage! (So many regrets right now ) Anyway I owe approx 104k at a fixed rate of 1.78% which works out approx £500 per month. 
I was thinking about paying an extra £150 pm off the mortgage which according to the mortgage over payment calculator will reduce my term by 5 years and 7 months so it'll be paid by time I'm 60 however I have seen an alternative strategy that I am considering; instead of paying extra of the mortgage I could put the money into a Stocks and Shares ISA which returns on average 6-8% per annum over a 10 year period. In approximately 16 years time I should have approximately £80k in savings and be earning enough interest to skim it off the account to start paying the monthly mortgage payments instead of using my wages. That way I will have a reasonable amount of savings to add to my pension and my mortgage will be paid out of a passive income. 
Whats your opinions please? 

MartialArtMan

Don't know whether to take the lack of response as a positive or negative so I'll just follow that strategy and report back in 15 years time

Bargainhunter30

  you will get mixed advice on here and I think it depends on your personal circumstances.  Investing in a pension would save you tax if you're a higher earner, but mortgage freedom may offer piece of mind. Everyone has a different opinion. Good luck though!