Today news arrives that the 31 year old father of two Mr Mashudur Choudhry has been convicted of terrorism related offences for going to fight in Syria.
Syria is currently a mess and going to fight there may be a bad idea especially as allegiances of different groups are murky and chances are people you consider on your own side will be trying to kill you for fighting with another group. Or worse you will be forced to work with groups carrying out attrocities and other crime.
However I do not think that it should be a criminal offence for people to go to Syria, even if to fight and any anti terrorism laws that make this a criminal offence are wrong.
On a related note, I doubt this legislation will be used to target non Muslims: There are many private security companies in the world that act as mercenaries and private militias. Many even have links to the government and rich and powerful people linked to the government.
There was a case a few years ago where a British PMC was caught and arrsted while it was preparing a coup in an African country. The company was linked to the son of Margareet Thatcher. I doubt this legislation would be used against these companies.
Then there is the case of the Israeli Defence Forces. The IDF are known and agreed to be subjugating an entire population and occupying the West Bank. I doubt that Any Briton that goes to train with or work for the IDF would be convicted of similar offences.