You can enter the country which its passport you own even if there is 1 day left on it. Other countries: no you cannot use this passport. Now, either apply for a new one while in the UK or before you go to the UK, apply for one at the nearest British High Commission.
Three months.
Britain is in Europe, so there is no passport timeliness requirement for a British citizen to enter the UK. If by Europe, you mean any non-British country in Europe, the requirement is usually six months validity, but individual countries may vary. A VISA may also be necessary to visit some former Soviet republics.
Yes
Yes, and Jamaica doesn't require Brits to get a visa.
I'm sure it's has to be more than 6 months now..
i have a uk passport with 5 months left can i travel to amsterdam for the weekend
You can travel with less than 6 months left on your passport to some countries, but it's recommended to renew it before traveling to avoid any issues at immigration. Check the specific entry requirements of the country you plan to visit to ensure your passport is valid.
You need a minimum of 6 months from your date of return
It is possible but the bearer of the passport may face difficulties upon arrival (e.g. questionings at the passport control). You may also require a passport that is at least valid for 6 months in order to apply for ESTA (which you should if you haven't done it before).
8 months
It is not possible to travel to Israel on a passport that is less than 6 months left on their passport as a passport is not a form of transport. You would be much better using an aeroplane or train if possble.
UK passport holders require 6 months left on their passport