Burqaa in the UK why is it legal?

I am from a country which is considered Islamic and every time i visit the UK i see tons of women wearing Burqaa in the streets of England and I find that disgusting and insulting to the British culture, a women in burqaa in the UK looks like a craw in a flock of swans. Burqaas are a great threat to security as well, in my country, Kuwait its illegal for women with burqaas to drive as it impairs there vision yet in the UK i ve seen it happen.A burqaa is also a great threat to security as you cant tell whose behind it it can be anyone it can be the most wanted man in the UK, i ve also seen women attending university in burqaas, how does the instructors know if thats the right student? why is it still legal??