iv been here 14 mate but when I travel back to uk for a couple of months as I will be next month, when I come back even with a visa I always but a cheap £10 disposable onward flight.
Iv been asked twice in the last few years ,emirate airlines. for a tenner not worth the hassle.
do some research, if you don't have a onward ticket leaving Thailand in the time permitted, whether it be visa exempt, or visa. You could be stopped boarding by your airline, so if you don't have a return ticket, a simple onward disposable cheap ticket will do,some people get asked some don't depend on your airline.
A friend of mine opened a account with kbank not so long back.
He took all the required documents, plus a bank statement from his UK bank account, showing a fair amount of money.
Told the bank he wanted to transfer cash in Sterling every month, to thai account less than a hour done sorted, but I recommend taking a thai speaking person with you.