It doesn't look like you have even completed or applied...if you had you would have a QR code sent to you so you can go and pay. Have you done that yet?
I flew Qatar London to bkk and they wanted proof of onward travel.
I showed them a genuine train ticket udon Thani to Vientiane, cost 3 us dollars and they were fine with that. Bkk immigration accepted it as well. Got it on 12goasia website
I got stopped for 30 minutes when I arrived in March, I had been here a lot though tbf. This time die 60 exempt..30 day extension and then went to laos and did the 90 day non o retirement. It expires on Sept 2 . Going back to uk on 27 Aug and intend to come back in March 26 on another non o. Hopefully will be bo problem as I have bank account and phone here now so intend to get the one year extension.