In the example given - Norwegian hubbing at Gatwick - Norway isn't a member state of the EU.
No, but it is party to large parts of the EU including, but not limited to, free movement and the EU has always sought to bring Norway in as a full member. The UK, if it abandons the EU, will be negotiating from a very different position. It is foolish to think that we will find it trivial to renegotiate all the benefits we're currently enjoying as part of the EU.