"Are you seriously saying that all the benefits given to the UK by the EU will continue when the land mass and population will be diminished?"

If you are referring to the "diminished land" caused by Scotland voting for independence, then by and large the "benefits" as you call them for a country of 58 million would roughly be the same as those for a country of 63 million taking into account of course that the payments and the UK is the second biggest net contributor will also pretty much remain the same.