I'm going to Bangkok (Thailand) in May for 1 week then flying to Phnom Penh (Cambodia) where i will probably be staying for 6months to 1 year.
My flight is booked to depart Heathrow in may and come back to England in October. On my flight slip it states that Thailand will require a tourist visa, will i have any difficulty getting this, i only plan on staying in thailand for 1 week.
When i get to Cambodia i'm gonna apply for a tourist visa for 1 month then extend it to a business visa. I've been told that i can do this unofficially and should be able to stay there for several months.
Please give me some advice.

Thanks