I know how to set up a menu and buttons, i’m just not sure how to do the rest.
What id like would be something simple like:
Player 1 gets first choice
Selects one of four images and that’s their character,
Then its player two’s go, etc until Player Four has chosen
And finally each player spawns and possess’ the appropriate character
?
You could use a simple int (1, 2, 3 or 4 is the player) use a switch on the int and after setting the player add one to the int.
Sure, the variables side is fine
I more mean, how do i differentiate characters and spawn + control by the players accordingly
Get the player controller from the int starting from zero then from the level blueprint you can use a possess node on the pawn you want to possess. On the level blueprint you can even get the reference of an actor in the map if you selected it.
Thank you thats a great example! 
One thing though, in said example it handles one character with just different colours,
If i wanted different characters (different models not just materials) but holding the same character properties, would i use a parent character class and use the specific characters as children?
or any other suggestions?
I know it is not really the same but in my puzzle RPG game I use a main block blueprint and then by right clicking on the main block blueprint in the content I select “Create blueprint base on this” to make as much derived blocks as I need based on the same actor.