Yes, knobbygb it is a UK company. Incidentally, on the cost of advance purchase against membership. If you are a member there is no cost for each individual stay - for the card owner. If you take in a guest there is a £15 per visit fee. So you can consider the possible benefits of a 12 month usage against the Standard Plus deal. Also, if you have a companion on this trip, that will affect the equation.
In my experience, they tend not to be crowded other than at the usual times of day. What you can get is a lot of coming and going with folks just stopping in for 30 minutes. So try and get yourself a seat in a corner out of the way.