In USA the evisa is for 60 days, than you can get an extension for 30 more days. Idk about UK. Yes, you need a flight booked out of Thailand within the 60 days. Can be to Cambodia. A side trip to Cambodia/Vietnam is an ez way to get the 30 days extension or Visa Exempt. The 45 days Visa Exempt has been reduced back to 30 days. As for hotel, it used to be the first hotel booking was sufficient. Maybe someone else can comment about this and UK requirements.
That's my point, you are not being honest with immigration, if coming in on a Tourist visa, but are actually applying for a job. Everyone knows how picky Thailand is about foreigners working in Thailand.
I was in the same situation recently, so I flew to Phnom Penh for a 3 day weekend. Got my new visa exempt stamp, and a nice little trip to Cambodia. No Problem.
I'm 62, and walk with a limp, which is at it's worst after 20+ hours of flying and layovers. Many times I'm directed to the fast lane. Now I ask, and they usually say yes.
If you are on a Tourist visa, a trip out of Thailand is required within the length of your Visa. I'm assuming 60 days + 30 day extension. So a ticket required within 60 days. You can book a cheap flight to Cambodia or Vietnam for around $50. There are other options . As often mentioned, Thai officers rarely ask for exit ticket. I've been asked maybe once, in many trips. However, airline gate personnel have asked me for an exit ticket on a few occasions. I recall one airline person actually counting the days on her fingers.