Cambridge engineering students, what grades did u get for AS(with UMS) and o-levels?

Hi i am kind of curious as to my chances of getting into Cambridge and wondered whether it was worth applying, considering the INTENSE competition among the international students

My IELTS scores are terrible........
Reading- 8.5
writing- 7.5
Speaking- 6.5 this is the problem
Listening- 8.5
OVERALL- 8
Cambridge says they want at least 7.0 in each element.
However, I do have an A for english for GCE O/L. Will this be a problem?
They only mention about GCSE and IGCSE not GCE.

As for academics, I received 10 As for GCE o/l s. I am an international student by the way ( I live in Sri Lanka ). I recently got my AS level results :

Biology : 293/300 - A
Physics- 300/300 - A
Chemistry- 298/300 - A
Maths- 292/300- A
Further Maths- 259/300 - A

I want to apply for mechanical or chemical engineering and my ultimate goal is to pursue a career in sustainability and renewable energy research. I am very determined to find a solution to our energy crisis and global warming ; to do that, I need to get into the best possible schools in order to get hold of the best research facilities.

As for my extra curricular activities : I don't have any sports or activities that I carried on for a long period
I did an intern at the Sustainable Energy Authority in Sri Lanka and helped raise awareness on Renewable Energy and how to cut down domestic energy consumption to the Sri Lankan public during an Energy Exhibition. I got to learn a lot about the aerodynamics of wind turbine blades,basically a LOT about wind energy and a slight idea of how coal plants work.
I am also fluent in 5 languages English, Sinhala (my native language), Norwegian, French and German.

I also read New Scientist every chance I get to update myself on the new technologies that have emerged in the field of Renewable Energy.

That's about it

Why I am applying to Cambridge is because of the AWESOME research they do on climate change and alternative energy, not really because of its prestige.

Your opinions?
BTW, is it harder to get into Cambridge as an international student?