I've never heard of the site let alone played there but this came up on my faceache feed
https://www.plymouthherald.co.uk/news/plymouth-news/mystery-plymouth-airsoft-arena-suddenly-9109223
TL,DR: Smokin Guns airsoft site in Plymouth is closing
Edit: from the comments on Facebook I can see why it closed. They did bugger all advertising, charged £25 for an hour long session and you couldn't use your own kit. Also there are accusations the owners weren't paying rent of staff wages, if this is true then quite frankly it sounds like the airsoft community in the area are better off without them