Currently, for travel within the EU and lots of other countries, your passport only needs to cover the duration of your trip.
However, post Brexit, if it happens on 29th March, we don't currently know, as that is one of the many things that is part of the deal/no deal/etc etc, so you might come unstuck if it changes to needing six months left, and you don't have this.
However, you might be able to get an emergency appointment for a new passport, should you need it, but this costs more, and there might not be convenient appointments available, if there is increased demand for example.
The passports issue is made worse by the change where you don't keep up to 9 months of unused time, if you renew early, which will probably cause more people to leave their passport renewal until later on, to avoid losing time.
This change seems quite short-sighted to me, as under the old system, you could renew your passport at quiet times of year and when you knew you wouldn't need it in the next couple of weeks and it would come back in days.
OP, if yours runs out in November, you may be effected by this if you want to travel from May onwards, to a country that requires 6 months remaining, which may include EU countries, post Brexit.