Lots of westerners in Thailand without Uni degrees hanging around looking for work. They using end up living very cheaply and then getting deported . You should have about 5000 -10 000 GBP in your bank account to make sure that you don't end up on the streets
If you do a 4200 Baht visa run from CM, then you don't need anything and come straight back. No nights out, no Flight ticket and no Condo contract. Met some of those border bouncers today
Its not the Thai immigration who insist on a return ticket , its some airlines refuse to let you board the flight because of no return flight . As you have such an unpleasant attitude , I will not be helping you