I deal mainly with fit young men and they routinely don't get surgery straight away for various reasons. I do not necessarily agree that they should have to wait or that they always need to wait but that is down to surgeons and bigger powers that be!

Often swelling or reduced range at the joint will mean that surgery may need to wait. It may be that the first surgeon you saw was not confident that he could help you, as you may have hoped.

I have treated many ACL repairs and a few ACL / MCL repairs (with or without Wikipedia reference-linkmeniscus repairs), of the ACL most do pretty well and some get back to very high levels of activity...a few don't do as well, for various reasons. ACL with MCL is more complicated, obviously the more unstable your knee is the more complicated the surgery is.

Personally if it was my knee I would probably opt for surgery as if the knee feels unstable with day to day activity then you are increasing the general wear and tear at the joint.

You are right to seek a second opinion, it will do no harm, as I said before let them know what you have been doing. Be careful at the gym, as certain exercises can cause a shearing effect at the joint...ie. knee extension (open chain), which will make it feel more unstable.

When you go for the second opinion be mindful that the 2nd surgeon may be friends with the first! That is not to say that they wont help you...just that they are unlikely to appreciate negative comments about a collegue.

Good luck, don't give up, keep seeing that physio and watch out for joint movt. (shearing / sliding) when you are exercising.