Checking the times, it seems to be operated by a BFS aircraft so therefore 737-700.

I’m not sure if LTN has any based A319s but it will be one of only three remaining 737-700 bases, along with NCL and BFS.

As for the website, I have difficulty finding airport website’s too while Googling, so many other results about car parking and flights top the list first before the offical airport website. I find checking Wikipedia for the airport and then External Links usually works.
http://www.london-luton.co.uk/