we sound very similar, although you are slightly heavier than me (5kg maybe)

i am also new to the sport, and have been through the dilemma of choosing my first board.
as arlo said, i went for a starboaard go 144 after hours of deliberation. good to learn, but will give plenty of enjoyment later down the track. but arlo's (and everybody else's) advice is well worth taking. a few demos / lessons i would say is the way to go. we are fairly limited here in SA as far as demos and lessons go, but given that luxury, id definately take it, then straight away buy something more advanced.
arlo gave me a few pointers at the weekend and helped a great deal. you may figure it out yourself, but will just take a little longer.
all the best with it mate.