Kit for Wedding Photo / Video

I'm doing a few video & photo jobs at a two family weddings later in the year. Both abroad in nice summer foreign locations, making lots of use of natural light (fingers crossed).

I'll be shooting on a GH4 (currently have a 20mm, and 18-35mm - metabones) and also have a Canon 650D too (10-20, 50, 18-55) (i know its not full frame).

Apart from this I'm in serious need of upgrading and purchasing new kit. I'm open to all suggestions of lightweight and moveable sliders, rigs, small portable light solutions, on-camera/ off flashes. A lot.
Yes I understand its a huge undertaking, and huge pressure for a newbie (I've shot two wedding videos already but have taking photographs for about 6 years).

If anyone has any friendly advice I'd love to hear...