The Acts of Union were in 1707, over a century after the Union of the Crowns. They were nothing to do with King James VI. The Scottish Parliament continued throughout the 17th century, apart from during the Cromwellian invasion.

By the way, England has been in regnal union with a number of places including Hanover, the Netherlands, France, Denmark (+ Norway) and Normandy.

Also the title was "King of Scots" not "King of Scotland", another common mistake.