Cambridge International Examinations and Pearson Edexcel provide useful online resources for candidates, including past papers.
Cambridge International Examinations
You can search for support materials, including past exam papers, for IGCSEs, O Levels and A/AS Levels by going to the CIE online resource centre.
IGCSE English as a Second Language new Syllabus information can be found at http://www.cie.org.uk/programmes-and-qualifications/cambridge-igcse-english-second-language-count-in-oral-0511/
Pearson Edexcel
You can search for past exam papers for International GCSEs and A/AS Levels using the Pearson Edexcel past papers search tool.