Good teachers get fantastic results and work long hours. Their work is never done and they get the most from the children.
Bad teachers typically come from crap universities (who did a turd course like social psycology and then stuck a teaching year on the end of it) and gained entry with only 2 Alevels and many have appaling spelling! Some show up at 9am, mark all books in the class and leave at 4pm and do not prepare for lessons.
In modern Britain, a good teacher is becoming increasingly hard to find. However difficult teaching may be though, they do get a LOT of holiday.
A good teacher works long hours, but crap lazy ones do very little and have a very cushy life.*
Should teachers strike? No, because the majority are lazy and really have no idea how easy working in education can be. I feel for the small number of good, hard working, decent teachers who genuinely do work a 50hour week.
*I have relatives who work in a school, I go into school myself for a technology project with Class A students (I don't go near the 'special' kids) and obviously I went to school myself once

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EDIT: The problem with many teachers is that they have NEVER worked outside a learning environment, which means many have no idea about the real working world.