Thai duty-free is one liter for alcohol. Same same for beer, wine, liquor, Lao Khao.
Personally I wouldn't exceed this limit. Thai Excise officials - outside of Customs - can be very "demanding".
And no, you cannot bring more in and declare it, and possibly pay duty.
Believe Australia is 2.25 liters. And that you can find this "Kentish Strong Ale" in Australia.
http://www.aclandcellars.com.au/beer...ps-finger-beer
http://www.purvisbeer.com.au/beer/Sh...ops-Finger-Ale
and a gazillion other shops.
FWIW, Beer Lao sucks in Thailand as it is usually ~ nine months old (per the bottling date), and is so far "off" as to be undrinkable. Chang (original?) is pretty bad, but Chang Export is acceptable, as is Sing(ha), assuming a recent - 2 weeks- bottling date.
Czech Republic #1 country in the world for beer
Lager? Yes. Ale? Definitely No.