Is it enough to believe in God and Jesus but not to subscribe to any church?
Yes, for it's Jesus who saves and not a church or denomination.
However, there's a difference between believing, as intellectually acknowledging something, and trusting Jesus, as in receiving Him as John 1 states.
If you're not sure of the difference, discuss it with God and tell Him you want to be sure of that relationship.
That said, yes, a good Bible believing church is hard to find these days but the benefits of belonging to one are there. If you're part of the body, they can help minister to you and you can find friendship and fellowship and support from other believers.
Going it alone is a rough road to follow.
I’m not a member of any church. You are saved by faith alone. not by going to church.