Where can I find English translated Clockwork Planet light novels? Are there online shops which sell translated copies?
The Clockwork Planet (『クロックワーク・プラネット』) light novels have not been licensed for English translation and distribution so far.
Yen Press has licensed No Game No Life, another light novel series by the same author, Kamiya Yuu; volume 1 was released in April 2015 and volume 2 will be released in July 2015. The highest chance of Clockwork Planet light novels being translated is currently through Yen Press, but Yen Press has not licensed the series so far. You can make a request to express your interest by sending a message through their contact form or by posting a comment in response to their new licenses announcement.