I  had a retirement visa for three years but for various reasons I have now returned to live in the UK. 

However I wish to return to Thailand  two or three times a year, a month at a time, to visit my Thai family.

I plan to use the visa on arrival, however I wonder as I was in Thailand all this calendar year until September 10, would the authorities demand I remain outside Thailand for 180 days before I can get a visa on arrival?

Thanking any replies in advance.

Your UK nationality does not qualify you for the visa on arrival, but under the visa waver program you are free to travel to Thailand any time without a visa for the purpose of tourism for 30 days (29 nights).

 

Be sure to say "tourism" if the immigration official asks for the reason of your visit, because there is a miniscule chance that if you say "visit my wife" a surly official may incorrectly berate you that you should have used a non-O visa.

OP, There is no 180 day rule.

However as correctly pointed out above , the io may question why you are not using non O with extension and reentry permit. 

However you mention "2 or 3 times per year" 

Zero issues with that.

Many tourists visit far more often than that each year. 

 

18 minutes ago, Maestro said:

Your UK nationality does not qualify you for the visa on arrival, but under the visa waver program you are free to travel to Thailand any time without a visa for the purpose of tourism for 30 days (29 nights).

 

Be sure to say "tourism" if the immigration official asks for the reason of your visit, because there is a miniscule chance that if you say "visit my wife" a surly official may incorrectly berate you that you should have used a non-O visa.

My wife died three years ago but I want to visit her daughters and grandchildren whom I am close to.

7 minutes ago, bannork said:

My wife died three years ago but I want to visit her daughters and grandchildren whom I am close to.

For the number of visits per year  you outlined you will have zero issues. 

As you are aware the visa exempt entry (30 days) can be extended by 30 days. 

you will have zero problems mate.  just come.  30 days, just say tourism, never mention your family.

9 minutes ago, nickmondo said:

you will have zero problems mate.  just come.  30 days, just say tourism, never mention your family.

 

Agreed. The people who have issues (mostly) are those who are doing consecutive border runs over an extended period.

16 hours ago, bannork said:

My wife died three years ago but I want to visit her daughters and grandchildren whom I am close to.

I am sorry to hear your wife died. I hope you are OK.