UK extend Visa ?

Just 2 questions if anyone has been in the situation before --- I obtained a 6 month visitor Visa to the UK for my wife in March, leaving lots of time for what was going to be a late May visit--I had a few minor medical problems, An umbilical Hernia which needed attention , & as I do next to nothing when I visit the UK, but I am quite active in Thailand, I decided I would have it done here closer to the time, & do some of the convalescing there-The colonoscopy that I also decided to have , discovered a very large bowl tumor--the happy ending to that was that it was benign , but took some removing & also put back the Hernia Opp quite some time. So now I have the position where my wife (who only wanted a 10 day visit) has a UK Visa cut off in 3 weeks & I am not really up to the travel yet---next month would be fine.

Changing the Airline tickets has been no problem.

1/ Is there such a thing as extension for the UK Visa once obtained--or do I have to go through the whole nine yards of interview etc again.

2/ Has anyone used the UK embassy in Laos when they reside in Thailand. Its an easier option than BKK as I live quite close to the boarder, I know of many Americans who have done their Wife's Visa's this way since they have opened there, but the American Embassy's does always seem a lot more user friendly then the others.

Thanks