Complex sentence: Formed in early 2008 (after George James quit his previous project and Andrew left his band) the pair pushed Georges 3D idea he had thought up in 2005 but had previously found no one to help him make it work.
Split into simpler sentences: Formed in early 2008 after George James quit his previous project and Andrew left his band. George approached Andrew with the 3D idea he had in 2005 and had previously found no one to help him make it work.