I think you did the right thing in giving her a graceful exit. But no way would I have booked her first class. She needs to learn how real people live. Get her a cheap ticket back to her parents.
I was in a similar situation - I moved out of my flat for a year to study at university (masters degree), and rented it out VERY cheap to an American girl I knew (and I was a bit sweet on her, but we never dated or anything).
On one of my home visits, she asked me could she fiddle the electricitymeter ( i.e. get the electricity for free - we both had friends who did it a lot). I said no cos it took me a long time to get the flat, and it was at a good rent, and I didn't want to risk being kicked out.
After uni finished, I came back and found she is still there. Asked her to move out pls. She went and stayed with her new boyfriend, but my flat was still FULL of all her stuff (she was a bit of a packrat). Deadlines came and went, one after the other.
After no progress, I laid down that on Sunday I would help her pack and move out. OK no probs. She came over, we spent all day packing. Right, where's the removal van? She booked a van like she said she would, right?
'Oops I forgot! I'll just ring up and get one." Babe, it's 11pm on a sunday, where are you gonna find a bloody van??
There's still lots more to pack, (did I say she was a real packrat? Boxes and piles of stuff everywhere in my tiny flat) so we agree same again the next sunday. Exactly the same thing happened. No bloody van. Plus her snogging her new boyfriend in the kitchen while I'm trying to sort out her stuff.
I'd had enough. The next day, I texted her that if she didn't move her stuff out, I would take all her knickers and underpants and bra's down to the local police station, and give them to the local cops ...
She hit the roof, was really furious at me, but two days later my flat was clear. Result! I wasn't serious about giving her stuff to the cops, I'd never do something sh¡tty like that, but it got over to her how I felt.
Later, I'm clearing up, and find equipment for fiddling the electricity meter, and realise she's been fiddling my electricity meter for months and months (friends told me she had electric heaters on all the time when they visited, even though I have a working gas fired central heating system).
I could have lost my flat and or/been arrested if the electricity company had found out. I'm glad she's out of my life.
BTW I did get a visit from them to 'check a problem with my meter' a few weeks later, but luckily everything was fine.
xTomato