A lot of people out there consider South Asian girls to be very pretty, honestly. Now, I don't know about the UK, but there is one particular race/gender combination here in the US that is found unattractive in surveys on a regular basis. I won't name them out of respect, but you can look it up. It might make you feel better about your own race.
I will say that you're probably nowhere near the bottom of the "pecking order," if you pay attention to that. Even some White girls feel insecure about their appearance. There are White girls that are considered ugly, get teased and excluded, or feel fat. People in general tend to have these kind of insecurities. It's natural to wonder why people are paying more attention to people that look different from you. There are White guys that complain all the time about girls going for foreign men and claiming they can't get a girlfriend because of it, for instance. Your complaint is likely more valid than theirs, but the point is that there are probably more people than you think that would be interested in you. When you feel self-conscious or undesirable, you just start looking at life this way... through this negative, jealous filter where everyone else seems to have it better than you do.
But what I think is that people who care more about a person's appearance than who they are inside are kind of superficial anyway, and that you're probably better off without them. Do you really want the kind of superficial, crude attention that some blonde girl in revealing clothing gets, or would you prefer to find someone who really appreciates your personality and your interests?
Being White really doesn't make life perfect by any stretch of the imagination, though. For one thing, people of other races are often jealous of you and resentful for that reason alone. They think they hide it well, but they really don't. At least you're honest about it, and that's always a good thing. It's almost like being rich and having poor people think of you as a "fat cat," but without the advantage of having money. There's this feeling that the sword of Damocles is always hanging over your head, and that everyone else who isn't White wants to see you fall because you're already too high up for their taste. To try and put this in British terms, I think all White people are basically regarded as tall poppies by other races here in the US.
I mean, I'll never know for sure if the people around me actually value me personally, or whether they just like the fact that my name is easy to pronounce and that my skin is so transparent you can see the veins in my arms all the way up to my elbows. The good thing for you is that anyone who does care about you... probably cares about you for who you are.
I guess ultimately, my point is that you have to learn how to value yourself and seek out people who are also willing to value you. It can be very hard, and it will likely take time. But I think once you find some friends in a supportive environment that accept you, all this stuff won't matter so much to you.