Movie Optimus Prime build

[Wombii]

I'd say the most common stuff for sticking styrene together in Europe is Revell Contacta professional cement and Tamiya extra thin cement. The Tamiya cement is completely liquid and is applied while holding the parts together, while the Revell is more like a glue with a very fine applicator tip. They both weld the plastic together. I'm using them both.
I'd recommend starting your own build thread and show us your plan and progress and collect your questions there. It makes it easier to look up later