AerBabe
Haven't flown a Chipmunk since I was in the Air Cadets (the hours I wasted dressing up in a uniform just so I could get the occasional flight...!!!), so I can't offer any practical advice.
But on the psychological side, everyone who's converted to taildraggers has been through the same "worried" phase! I couldn't believe it when I was sent solo - didn't the instructor realise that I was just having a lucky day, and that really I didn't have any clue how to land? He had much more confidence in me than I did!
It turned out that he was right! Soloing a taildragger was almost as good as my first solo, and I'm sure it will be for you too. If he says you can do it, believe him and do it before he changes his mind!