I personally would not worry too much about the rust, it can get a lot worse but will really take some time, remember the bike is only original once, people demonise rust and while it is bad it will be a long time before it compromises the integrity of the frames structure.
If you want to see bad rust have a look at some of the other threads, my thread on my 1958 Jacques Anquetil, which is further down the page, enjoy the bike mate.