What does she have in her Thai passport as the UK no longer ILR stamps in passports or issue resident cards, it is all e visa (ie all online), if your wife has a UK stamp in her passport she should have already applied to have it all transferred to online, but this might already be the case if she has a UKVI account, the she will have an e visa already https://www.gov.uk/evisa/get-evisa-settlement-uk I am assuming you are talking about her boarding a flight back to the UK as she only has a UK e visa airlines are conncted to UKVI and can see her details, the importnat issue that her details ie passport number etc are updated in the UKVI same as phone number etc, see link below IF she still has a ILR stamp in her passport then these are still valid but she needs to get her status put online