>>3686813he is technically capable of "excercising his will" only through "ministerial advice", which in this case means agreement of the prime minister. the minister is held responsible of all the actions performed "according to the crown's will", and so they are subject to judgement of the parliament, which then, according to their unorganised law, also has the authority to limit the extent of the minister's power (e.i the rest of the british law) and punish him for unlawful conduct, thus not directly going against the crown. apart from that, "the crown's will" is not deemed to be true unless confirmed by an institutional procedure/ministerial advice, forms of which are regulated by the "binding conventions".
so, to put it simply, monarch can try to ask the prime minister (the agent of the crown's will) to dissolve the parliament but he can just refuse to and it will be "legit".
britain is a raped state in its legal foundations.