On the topic of the FTPA, it’s worth looking at how the Irish Constitution (building in Westminster practice) deals with the power of the executive to dissolve the legislature. #IFGElections. 
Key point is that it makes it clear that an executive that has no majority has no right to dissolve: the head of state can refuse (and would presumably be likely to do if an alternative government can be formed).
We might be hesitant to give by statute even that discretion to the monarch.
But you could keep a UK version of Article 13.2.1, but convert 13.2.2 into a requirement to get the agreement of the Speaker, who could refuse if he considered the Government had no majority and that an alternative could be formed.
