Are you looking to combine these logos just for use on screens, i.e. the Internet, or are you interested in having a logo that is fully scalable, in other words in vector format? The latter would be if you intend on using for print, and would like the flexibility to enlarge the logo if necessary. The letter E logomark in the London Environmental logo has 3-D Photoshop effects, and those can be problematic when enlarging them.

Dear Project Owner,
Also, can you upload a vector files of both logos?

Thank you