Return flight back to LOS

Hi All,

Looking at flying back to UK next month but not sure of a return date and it seems a one way is my best option, a friend of mine would like to come back for a holiday when I return ( September 2018 ) looking at some UK web sites and there are some bargain holidays when you book from the UK, example 14 nights Phuket half board inc return flights 400 quid, I am on a single entry non O based on marriage and doing my 90 day at Buriram end of this month, if I got my re-entry stamp at the same time and fly back to the UK beginning of next month and then return in sept with my friend on the 2 week holiday in Phuket but miss the return flight back to UK and make my way back to Buriram, can anyone see a problem with immigration.

Thanks in advance.