My garden has suddenly developed a massive growth of thorns they are all over the garden so how can i kill them i cant even cut the grass for them its driving me mad as they are quite thick and long?

It sounds like your garden is a loss this year. But if you want to get rid of the thorns and if you have a way to place a fence around your garden, then goats are your best solution. If you get the right kind, you could have some nice pork chops when they are finished.