If you don't mind me asking, where do you come from OP?
I'm not British, and I don't wish to sound rude, but a lot of women in England are chubby (hence the high obesity rate), so I really doubt guys here are looking for 'stick insects' (in fact, I don't think any guy anywhere in the world is looking for stick insects, unless they have some strange fetish for it, most guys are just looking for a woman in good physical shape), and they are more likely to be found with someone chubby.
If you're self-conscious (sp?) about yourself then see if you can find a gym and go there regularly whilst at uni, where you might not only loose a bit of body fat, but also, possibly, meet some sensible guys going to the gym for the same reason? You also have to make yourself more approachable, think about your good attributes...and also socialise more with a lot of people boys and girls.