Well, Edward VI was 16 when he died, so he was certainly of age to marry and father children. Lady Jane Grey was 16/17, and Catherine Grey and Margaret Clifford were both 13, when they were married off in order to quickly provide Edward with some suitably Protestant heirs. Their husbands Guildford Dudley was 16-18ish and Henry Herbert was 15, basically same age as Edward (Andrew Dudley's marriage to Margaret never took place I believe, and he was a far bit older anyways).
After the Rough Wooing failed and ended any chance of his marrying Mary Stuart, I wonder how great his chances of making a grand foreign marriage would have been. Certainly no Spanish, Portuguese, French, Italian or Austria would agree, leaving basically the Scandinavian states and north German princess, รก la Anne of Cleves. A daughter of Christian III of Denmark-Norway or a daughter of Gustav Vasa, or Anna of Saxony. From what I can see there were no graaand fabulous foreign marriages available and ofc the necessity of securing the succession would come first.
Edward knew very well his sisters were both of questionable legitimacy and likely to revert England to Catholicism (since Elizabeth wouldn't dare usurp Mary's place); as such there was a certain desperation to beget properly Protestant heirs.
He could have married Lady Jane Grey and attempted to father a child from her. As Queen-consort she would be crowned and annointed and seated at the very pinnacle of power when he died, so if the young King's last exertions failed to impregnate her, it would be easier for her to slide into a new role as Queen-Regnant. He could even associate her on the throne with him like William III and Mary II later did, or at very least empower her as much as possible to ensure her succession as either Queen-Dowager & Regent for their unborn child or Queen-Regnant in her own right. At the same time he could have married off Catherine Grey and Margaret Clifford to loyal Protestant husbands in order to provide him & Jane a batch of nephews and nieces to serve as spare Protestant heirs in case both Edward VI and Jane's second marriage (whoever he might be - Edward Courtenay would be ideal LOL) were childless.