hey : ) im also doing ocr gcse cs and although i havent really found any great websites except for some parts of bbcbitesize, the two youtube channels computersciencetutor and craigndave have videos covering the entire spec in detail. For my mock i used only computer science tutor's videos and somehow managed to come out with an 8 although ive been incorporating more craigndave videos into my revsion recently (i only discovered them after mocks hence why i only used computerscience tutor beforehand)