The demand Ana- is to leave the EU and put limits and controls on immigration- and at the same time have unlimited access to the EU markets without penalities or tariffs.
It is unreasonable, pie in the sky, and it was very clear from EU rules re negotiations in case one country leaves, right from the start and loooong before the vote. A leaving country has NO right to taking part in negotiations. Free movement of people is one of the absolute basic tenet of the EU agreement- why should all have to adhere to it- but not the UK. When the UK already managed to opt out of Euro and other parts.
Have you ever played cricket, or Monopoly - with different rules and different values for different players. Well, we all do with our grand-children, to some extent... perhaps- until they are about 5 or 6 ...