yep I'll echo what others have said, buy with your heart not your head, biking is about passion.
Don't buy first bike you see, try to save up more than £800 as it's not going to get a great bike... remember milage on a bike does matter, with most sports bikes showing big wear to suspension / brake calipers etc by about 20-30k miles. If looked after they will last a lot longer, but buy a 30k mile shed and it will ride horrid and fall to bits. (not to mention be a never ending money pit)
Don't let the power or engine size of a bike scare you, most bikes bar a very few v twins and maybe Busa and such like can get you in trouble if you keep the revs down... keep the revs down and all is fine.
It's all relative though, I remember coming from a R6 and jumping on a Busa demonstrator, first set of lights I came to, they went green, but the traffic pulled away and I was left in middle staionary... reason, I gave 600 class throttle and instead of moving just lit up rear tyre lol
Anyway i must have liked the tyre smoking experience and went back to shop and bought one
I would save up £1500 or abit more and buy a CBR600, it's deffo where the money should go... you could then get a sub 10k miler in very good condition (and pretty much spotless)