H2Pots, you will be welcomed with open arms at the Marshals Office, at the rear of the Grandstand, adjacent to the Manx Grand Prix 
office.
I marshalled last year, and it was a rewarding experience.

Just as an addendum to the Live Streaming, the Manx Club are over the moon with the response. I can't give you the exact numbers of hits, but it is huge.

The Manx Grand Prix is enjoying something of a renaissance this year. Much as I love the Classic TT, to be honest, some of the racing was not close, or closely contested.
On the other hand, all barring one of the Manx races saw the lead changing many times, culminating in a 5 second win today for Matt Stephenson, and 5 seconds was the largest margin on that last lap.
I had no idea who was going to win each race, and I don't care that much about superstars, i would rather have close racing.
Finally, I really appreciate the effort everyone is putting in, and who know, from this grass root racing, a new star may appear.
The TT could do with some new raw talent, the Manx has proved to be the perfect training ground for almost 100 years.