it doesn't matter where you live,as long as you have paid in more than 10 years you are due a pension. If for example you only have 10 year if you lived in the UK you would most likely be entitled to pension credit which would top up person to a government minimum. If you don't live in UK you only get the amount payable of 10 years contributions . I believe this is also true of the all annual increases .
ok from what I understand, you need a rental agreement in koh samui immigration but not sure if it needs to be for any particular amount of time. Can't you ask them ?