You already know what the website says. Most claims are dealt with in considerably less than 7 weeks.How long does it take to process a working tax credit application?
Well not because she is Thai, but possibly because HMRC did not know about her before? Is that the case? Does your wife have a NI number? When did your wife first arrive in the UK?Will it take considerable longer because my wife is Thai?
If I were you I would wait until early February and if the claim has still not been decided in your favour, I would think about contacting your MP, and ask him/her to chase the Tax Credits office.