Andy, almost everything depends on how much and often you think you'll be skiing down. If you're going to be skiing downhill very much, a cross-country ski will take a lot of getting used to. THe problem is, that anything you add to provide more control on descents makes the rig much heavier and really detracts from the enjoyment when you're on relative flats.
On flats and mild hills, an XCD setup will provide all the support and flotation you need unless the snow is super-deep and super-light. I'm a longtime alpine and randonnee skier (if that term is foreign to you, it simply means that I do quite a bit of hiking up mountains in order to ski back down them). In THAT scenario, it's fairly important to have fairly solid boots, bindings, and skis in order to provide the best performance for the downhill portion of the day. That all adds weight, though.
This past winter, I did quite a lot of cross country skiing in the area surrounding my house. That terrain is mostly flat with mild ups and downs thrown in for variety. When I started early in the winter, I would plod along in my alpine touring setup with moderately heavy boots, alpine skis, and skins (I didn't own any cross country gear). My wife joined me on a few outings and she was using her XCD skis. I was doing about twice the work that she was and I was going slower. She kept after me until I finally broke down and bought some XCD gear. The skis I bought are Alpina Woody in the 190cm length. Here's a website with the specs:
If that giant URL doesn't open, just Google "Alpina Woody cross country skis" and you'll find them.
I weigh about a stone less than you and I bought the 190cm length. I actually skied on them a lot once I had them. We had a LOT of snow here in Jackson Hole this winter, and I never really found myself sinking in all that much. There are similar skis that have a little more width if that really concerns you, and in an XCD ski a little extra width really doesn't add all that much weight.
The bottom line is that I was able to ski much farther and much faster with way more comfort on the XCD skis than when I was trying to "get by" with my randonnee gear.
XCD would be my recommendation.
Good luck and have fun!