Hiya Luke
Just a quick bit of advice about starting to get a battle scene going. I'm currently on 3 2x4 table in my garage with random bits as terrain and was wondering where would be a good starting point to getting mats like yours. Would you suggest the mat first or propped terrain etc... I'm at a bit of a loss
Id get a mat first and foremost. It really determines the color scheme for your terrain. Secondly, there is an advantage in doing a wilderness themed board as you can make the terrain yourself, cutting and chipping foam to make rocky outcrops, use pebbles and lichen for scatter terrain. City boards are great, provide for a more varied set of terrain that might be better in the long run for actual gaming, but can be a bit more expensive. Frontline Gaming makes some great cheap city terrain though. The GW stuff is awesome and really competitively priced compared to other 3rd party companies though.
I wrote an article on making terrain if you want to check it out. might help!
http://www.frontlinegaming.org/2018/04/27/cheap-and-easy-diy-terrain/
All good advice from what the others have said. Yes I would go for a mat first...and a double sided one is a good idea. That gives you your foundation then build up from that!:) I am meaning to make some terrain videos in the near future:)