Thanks for the honest responses all, and apologies for the slowish reply!
Weight - well, it's fluctuated between 12 and 21 stones over my adult life, although it's largely been at the top end of that scale. I've an extra incentive to shed pounds now, as I've recently been diagnosed with a few health issues.
Living at home - I went to uni with every intention of not going back home, but I returned after graduation (16 years ago) and have remained ever since. I bring in an OK salary, but would probably struggle financially if I had my own place (plenty do, so it's no excuse, I know!).
Lack of relationship experience - I had some pretty brutal rejections as a teenager which, in hindsight, I partly brought on myself (I was WAY too intense), but they've made me wary of asking anyone out ever since. My one brief relationship was over a decade ago, now _ it never would have happened had she not made the first move. We dated for a couple of months, and parted fairly amicably, remaining good friends until bout 18 months ago when she, for no apparent reason, stopped responded to my e-mails. It still hurts, but heigh-ho...
I've always been pretty geeky, but I know that's supposed to be no barrier to a relationship, especially not these days. I do envy younger geeks, though, as they don't seem to be subjected to the same level of opprobrium as we were 20 years ago merely for being 'different'.