I guess its down to how happy you are with you country and government and if you think you can do better or enjoy your life somewhere else.
England is an ok place to live, although very expensive but i just about survive. It's a very crowded country and traffic in most places is so bad it's not even funny. Taxes are high here, especially for fuel and running a car costs thousands a year.
I would love to live abroad for a while, dunno if forever cos have grown up here and consider it home. I have always wanted to go live in Finland for a while as I love the people and lifestyle. Plus compared to England its just sooooo clean. I hate the way in every town/city in england the pavements are stained with chewing gum which has been left on the ground. Makes the place look very unclean!! In every other country I have been to I have not seen this.
Immigration is a huge issue in this country. Being an island nation i think most people here hate the thought of 'foreigners' coming to live/work among us. Plus as we are overcrowded, the amount of foreign people coming here is putting a strain on our schools, hospitals as well as making the competition for jobs much more fierce. I live in a small town and we rarely used to see people from round the world here, but now we have South African, Australians, Polish, Bulgarians, Scandinavians and people form other countries working here too. I like it, as well as meeting people from different places so i dont mind.
I think people should be able to live/work where they please but there are limits to how many immigrants one country can actually cope with, so that has to be factored in somehow.