The effect of the French Revolution on British reform is hard to judge. On the one hand as you say, a conservative and reactionary (later "Tory") ideology did develop in the 1790s centred around a greater reverence for the monarchy, Anglicanism and the constitutional status quo. Pitt's measures of repression and the birth of conservative loyalism at a local level did arguably deal the reform movement a blow. But on the other hand, reform had already come to a halt before the Revolution began. Pitt's efforts at piecemeal parliamentary reform failed and he resigned himself to defending existing practices. Without war, it's probable that Pitt's agenda in the 1790s is going to be about economical and financial, not parliamentary reform (i.e. resolving corrupt practices within the state, fiscal reforms, also abolition of the slave trade). Plus without the socio-economic upheaval of the Napoleonic Wars, is there really going to be the same impetus for reform which led to the 1832 Act? Also there's O'Gorman's argument that the Conservative reaction had been building up since the American War of the 1770s, which is questionable but something to consider.
Without overseas pressures, Pitt's longevity in office will probably depend on the extent to which Fox is a threat (and thus how much the King needs him as a barrier), and the extent to which he is successful in fighting "Old Corruption". If Fox stays on, I could see Pitt staying on through the 1790s, possible into the early 1800s. And I very much doubt that he's going to be able to pass any parliamentary reform in a stable political climate considering how his administration depended upon an aristocratic broadbottom base. If Fox goes, then it will probably be a grandee like Addington or Portland in charge who probably isn't going to be responsive to the most limited of reforms.
Honestly, I don't think that the absence of the French Revolution is necessarily going to lead to quicker reform. There had been calls for reform by a Country interest for the whole of the eighteeth century, so it's possible if the circumstances are right down the line, but I think it would take a large socio-economic or international crisis like OTL which you can't really predict or extrapolate from pre-1789 OTL circumstances.