If it was first registered in November 1946 that probably makes it a 1947 model. The motorcycle year was not a calendar year running from January to December but rather from about September/October when the factories announced their next years range. Traditionally this was in time for the Annual Motorcycle Show held in London in November/December where the next seasons bikes would be shown. World War II had interrupted play in 1939 and things didn't really get back to normal until the first postwar Show in 1949. It took a little while to clean up after the war finished and get things back to normal.
Your bike is definitely not a prototype, the ES2 had been around for donkeys years but if I remember rightly 1947 was the year Nortons fitted tele forks and rear suspension to their road bikes so you are in luck there. They are an improvement over what went before.
The alloy mudguards are absolutely period sporting fitments that many clubmen fitted. Your bike is very typical of the time and personally I'd leave it like that. There are very many old grandpa's who will smile broadly when they see it and bore you silly with their memories.
Basically this ES2 is a good sturdy roadster capable of taking you anywhere you want to go at a reasonable pace. Spares are easy, information is plentiful and there is a hardcore Norton world that will help you keep it on the road.
Cheers,