Can someone point me in the direction on how to make a vertical flyout menu please
Thanks in advance

Try Admin > CMS > Layouts > Site Navigation.
In the Datasheet View set your menu items to a product for example
T Shirts = products.php?category_id=1
and specific products such as
Red = product_details.php?category_id=1item_id=7
Green = product_details.php?category_id=1item_id=8
Blue = product_details.php?category_id=1item_id=9
Update all these.
 
Then go back into Site Navigation and select the Tree View.
Here you can assign the "Red", "Green" and "Blue" items as fly out menus to the parent "T shirts"

Thanks Ned, I thought of that but that would give me a "horizontal" flyout menu on the top of the screen
Is there a way to make the top menu go vertical down the left of the screen?