Do u need your husband's money in order to buy it or you plan to cut your household contribution. If not, u don't need anyone's permission.
If prices fall 30% and the tenant does not pay you, can u afford to pay the mortgage for half a year ? Cause u need 4 months to get the flat back, renovate and rent it out again.
You say u have 200k cash and 300k shares left after u buy, is that money yours alone or together with your husband?
Worst case scenario :If the stock market goes down together with the property market, u will be unwilling to sell your shares at a low price. Assuming that the money is yours only, how long can 200K last if u need to pay the mortgage with no renter.
You say you will not work in the future, then who will pay the mortgage if things turn bad, ie. tenant does not pay rent or no renter for a while
If that 200k cash is the family's cash pool, then it is too risky if the worst case scenario happens.