Crush did you see This Morning yesterday? there was an item about a new breast increase procedure nicknamed "The Lunchhour Boobjob"
They do it via local anaesthetic. They numb the boob then make a small entry point underneath (it's only a small hole) they inject more anaesthetic into the breast, and then into the same needle they put some filler, the same stuff they plump up people's lips with. They inject it in to the part of the breast you need it in, and the effects are instant, and really natural. Takes about half an hour, costs about £2,800 and is supposed to be painless during, and not too sore afterwards.
They showed you a woman getting it done, she had lost some weight and her boobs felt empty. They injected 1oz of filler into both breasts, into the part above the nipple where it was flattest. They plumped up really nicely, you could definitely see the difference, although they looked really natural. The surgeon said he could add more filler than that though, it's just she only wanted to fill her old bra again.
The major downside to this procedure is that the filler naturally dissolves over time so it generally only lasts two years, BUT I think it's also a benefit. No operation in ten years to remove an implant and leave you with empty boobs.
I think it's fairly new so I doubt it's available on the nhs yet but thought I'd mention it anyway, it's a LOT less invasive.
Just wanted to say I totally understand why you would do this, maybe I'm not being neutral enough for MN but I say go for it, life's too short to be constantly insecure over something you can change. I need mine hoiked up (didn't wear a bra for years in uni, they're on my knees like bags of blancmange) and if I ever get the chance to get an uplift, I'll jump at it! hth and good luck. x