Hey Blueseven, all the above is good advice. I have a Bic Techno 283 which is 150 litres. Yes you can definitley learn on this, but it may be a bit wobbly for you in lite winds with your weight. But this board or a bit smaller would be great when you are ready to plane and get in the straps. A big volume board is much more forgiving and will allow you to learn things like carve gybes much quicker. Then when you jump on a small volume board, its just a matter of refining and adjusting your technique.
But Gybsports is on the money, in fact I would recommend lessons, you will learn more quickly and avoid learning poor technique which you could have for years or ever, and you get to use their wide style learner board to save you buying one. I wish I had lessons when I was learning, would have saved me many years of frustration.