Parliament is unlikely EVER to have another referendum. Having asked THE PEOPLE what they want, they couldn't handle the answer (as shown by nearly 3 years of procrastination, to the detriment of other Parliamentary business).
Thatcher disagreed with referenda, one of only two areas where I admire and agree with her ;-)
[Because you're bound to ask otherwise (LOL), the other area was the very tough stance she took representing our country within the EU]
didn't know how to, I suppose. There are many ways to leave, all with many adherents, and balancing the competing demands of multiple little factions is seldom going to be easy. May is I think particularly dogmatic, which makes matters much worse; but I can't see any subtle diplomats among the possible replacements.