i don't know how old you are Dave, but only the very youngest AB-ers will live long enough to potentially see the UK become a republic.
The first problem is the other states who share our monarch as their head of state. Whilst some have already started the transition to republics, others have not, with some even saying there's no plans for a referendum any time soon. Agreement to abolish would be needed with all these states; practically, it would be simpler if they became republics first.
Next problem, no political party with even a marginal chance of getting enough seats to form a government (either on its own or as part of a coalition) has republicanism in its manifesto. Labour haven't debated the matter at its annual conference since 1923, and even the SNP have said a post-independence Scotland would not seek to become a republic. A pro-republican party will have to get itself elected first. things may change in the future but it's pretty unlikely now.
Next problem - having decided to abolish the constitutional monarchy, the administration would need to decide on the form of republic. Should the elected head of state be just ceremonial (as in Ireland), or should the head of state be "the executive" (as in the USA)? How would this be decided - by referendum, or imposed by the governing party?
Having decided all that, the constitution will need to be changed to accommodate. It's said the UK constitution is unwritten, but it's not. It's true none of it is in one place, but there's many rules and regulations written, here and there. It's likely to take years to unpick that.
it may be time to consider republicanism, but we're at least 50 years away from it becoming reality.