Would Thatcher have stopped the boats?..

There are fake refugees.
People from safe country bogus asylum seekers, illegal immigrants, call them what you will, but there are people who are falsely seeking asylum with no need to.

Illegal immigrants come to this country and falsely seek asylum, get it?

Essentially that's ^ waffle. If Sunak invoked international law he would not be "doing what the fuck he likes". The government, any government, can invoke international law and/or alter, amend or withdraw from any existing law/s. Laws are introduced altered amended and repealed all the time. In spite of what you obviously think, man made laws are not is set in stone. 

You mention "the rest of Europe's leaders", who exactly are you talking about? Europe is governed by a cabal of unelected commissioners who sit behind closed doors in Brussels, these people are are the architects of the almighty cock up that is mass European immigration. Are you aware the EU imposed immigration quotas on every EU state and threatened huge fines for any state who refused? Perhaps this is why the EU are turning a blind eye to hundreds of thousands of illegals who are fleeing the safe state of France for England. Which is why Sunak should, and with a sense of urgency, invoke UN law to stop the illegal invasion which is a clear threat to this country.

Now, you need to get your head out of your EU/minority appeasing arse so you are better able to see what the fuck is going on.