I would make sure that a bike bought to ride in Thailand was a ‘transition’ bike.
There’s no sense in getting the likes of a Street Triple out there (for here after riding a smaller bike I’d go along with you though).
In your position I’d get a Honda CB500X. They’re fast enough, reasonably economical, reliable and they look fun (to me). Think they’re even made there… A great run around. Set you up for (possibly) bigger bike when back here.
And Rachel, only buying a bike with your heart is bollocks. If I’d followed your advice I’d have a Guzzi California Custom 1400, a truly wonderful and gorgeous looking bike. Completely impractical, too expensive and would have required a new storage shed (adding ~£1.2k to the price!). Don’t fall for the advertising myths.