Lets' say me and the wife (Thai) fly over to the UK on single tickets, this isn't a problem for me as a UK citizen but as she is Thai would this make any problems either leaving Thailand or entering into the UK.

She will have a 6 month family visit visa in her passport.

The main reason for not having a return ticket is we don't know the exact date of return, it could be a few weeks or a month.

The main problem you will face is finding an airline that will let you fly with a one way ticket, I know it is not a requirement for a UK visa but most airlines seem to be reluctant to let people fly to the UK on a one way ticket.

Having a one-way ticket, is not an issue, as they dont check..., but what you will find is buying a one way ticket, more expensive,so sometimes a return is a cheaper option, maybe buy a ticket that is flexible, could be the answer.. ??

Having a one-way ticket, is not an issue, as they dont check..., but what you will find is buying a one way ticket, more expensive,so sometimes a return is a cheaper option, maybe buy a ticket that is flexible, could be the answer.. ??

The airline will

There is no requirement under the UK immigration rules for a visitor to hold a return or onward ticket in order to enter the UK.

However, they do have to show, if asked, that they will leave the UK at the end of their visit.

So UK immigration do sometimes check and may ask to see either such a ticket or evidence that the visitor has the means available to them, from their own resources or a third party's, with which to purchase one. Especially if the visitor is entering with their British spouse as they want to be as sure as they can that the couple are not using a visit visa to by pass the settlement rules and overstay.

If the visitor is unable to show either then they could be refused entry.

The reason airlines may be reluctant to board a visitor with just a single ticket is because under IATA regulations they are subject to a $20,000 fine if they knowingly carry a passenger who does not meet the entry requirements for their destination.

Most of, if not all, the main airlines are aware that a visitor to the UK is not required to hold a return or onward ticket and so if that passenger were refused entry by UK immigration then they would not be liable for this fine and so should board her with just a single ticket; but you may have to argue the case at check in.

However, as said above, it may very well be cheaper to buy a flexible return than two singles.

I did this a few years ago when travelling back to the UK with my girlfriend (now wife). We were flying with air India who weren't going to let her travel with a one way ticket. After a lot of discussion I had to sign a waiver to say I would be responsible for any costs if she was refused entry. At uk immigration they didn't ask to see a return ticket so all was fine in the end. However, I would suggest either checking with the airline or even better buying an open ticket.