What you're asking is 'what is a nice place that offers direct connections to Thailand?'.
If you mean 'non-stop', the best place is probably Istanbul. Nice city too.
The other options is 'easy transits', which I assume isn't the same as flying back to LHR with you and then to BKK. Have a look at Milan, Rome (she can fly to BKK on QR) or Venice (back with EY).
Hope this helps a bit.
