Hi there,
I'm sorry it took them so long to figure out that it was an ACL tear.
Denmark have as good, possibly better healthcare system than the UK, so make deciding on the surgery or not your issue rather than worrying about where to do it.
You say:
"After I went for physio and I found it to hard to complete so I have kind of given up trying some exercise to build my quads to support my knee"
Did you mention that your were struggling with your exercises to your physio? Did you make attempts to get your pain under control with anti-inflammatories and pain relief via your doctor?
Did you actually follow an ACL rehab program after you found out or just have one physio session?