Why do they head for the UK?

‘Hundreds’ of migrants now target Eurotunnel every night

I wonder where they come from and why they head for the UK.

They are from Africa and East Europa because the livinig standarts are there much lower then in the North Europa.
Why would they go to the UK? - Perhaps the immigration laws and the treatment to the immigrants are in the UK more liberal then for example in Germany.
THe problems are known, but the solutions are unknown
We in Russia have the same problem with the the huge immigration stream from Central Asia.