Hey,
I'm applying for the 2012-13 academic year. i'm applying to the following Colleges/ Universities:

1) LSE
2) Kings
3) QMUL
4) UCL
5) Nottingham
6) Trinity College, Dublin

I secured the following score in my IELTS exam
L-8,R-8,W-7,S-7,Overall-7.5

Is it good enough for the above mentioned?

An overall score of 7.5 with no less than 7.0 in any subject should be enough for all the colleges you mention (at least it was for the 2010/11 applications when I made mine). Why don't you have a look at the program's websites?