What happens when England and Scotland make an union in 1440?

[SpecterD 0]

To give some context for why I'm asking this question, first of all I have seen that when you play as Austria, and you form an union with Hungary (modern day is the start date in which I did this) you can form Austria Hungary before you form the Austrian Empire, making you basically skip that, but the question I have is that since England and Scotland united via a personal union I believe, I thought that it would work like with austria and hungary and would let you form the United Kingdom or something like that, I just haven't been able to make an union, I vassalized scotland and have an alliance with them as well, everything I have ever tried that somehow raised the odds of making an union and scotland still denies it, I just need to know if what I think actually happens or I'm just trying really hard to achieve something that doesn't exist. Thanks and sorry if my english is not very good but I'm not a native english speaker.