Or how about choosing a windsurfer instead?

I've found the Starboard Carve one of the best for upwind work, although my technique has improved enormously, and it's a very forgiving board, so all-in-all, I'm happy with it as a combo for me.  It pays to test them if you can, but Starboard is the 'modern Laser' coveted so often on here as the general recommendation for a newbie.  The will also hold their value reasonable and you can P/Ex them if you want to move into a different direction- maybe a full-on longboard (why oh why, dinghy sailing is superior...) or Freestyle.  Pretty much slalom, speed and formula are out of the picture inland.  

Ideally I would swap it for a 140L board as this gives a little more volume for the light winds and restricted access waters (marina setting) to the sea.  I have one sail out there, a 7.5 Natural.  If I could up this to an 8.5 I'd also be happy... but that requires a new mast and boom, so again, not worth the aggro. 

Yes, 140L in a standard freeride board is easily uphaul territory.  I sail a 121L Carve and can uphaul simply enough at 95kg, but I used to have a 140L and 155L and these were more than easy... so 140L for you is no probs.  

200L barn doors... you'll be flogging it and buying a laser before you know it (and you wouldn't be wrong to do so).

As for the Kona in Graeme's suggestion... yep, it's a much bigger volume, but the stepped hull makes a difference to performance over a beginner board.  I loved my brief escapades with one, I think it really is the ultimate board for dinghy sailors without going down the purely beginner route.  But they look ridiculous, suffer from late planing and are a bitch to carry around as they're so heavy.  If you do buy one, do not buy the rig... it's sh*t and goes better with a modern sail on it.