Are there opportunities via the university here she'd planned/hoped to go to where she could do a year studying/working abroad as part of her degree?
Many also do short term summer placements abroad. That might be a good backup option if there isn't time to sort it out yet now.?
Whatever she chooses, and whether you fund it or not, I'd try not to let your worries run wild, or your fears about her staying their "forever" and that you'd miss her too much.
Ultimately she is an adult and it's better for your relationship in the long term for you to just trust, support and guide her in making her own decisions, encouraging the exploring and taking of opportunities where they present themselves - and knowing you are always a safe place to return to (physically and metaphorically!) if things do go wrong/relationship doesnt work out etc.
She'll learn so much from the whole experience, good bits and bad bits!
I think as mums we will always worry about our kids making the "best" choices and being safe, but that's for us to deal with, not to burden them with being responsible for our emotions, and end up making choices that WE think are right for them rather than letting them find their own way amd build their own judgement and resilience.
I do think, although its reasonable/to be expected that you feel emotional about the distance, missing her and cautious about the practicalities of the change of plans, YABU if you are sharing your worries with her as outlined in your OP.
If she chooses NOT to go because you poo-pooh it/don't agree with it/refuse to fund her studies/ridicule the length of the relationship/minimise her feelings/tell her it's a ridiculous idea/scare monger/tell her she'll be homesick/scoff at her lack of work experience etc. chances are you will create an insurmountable distance between you anyway.
My 18 yo also off to uni this September, which will also include tome abroad, and im simultaneously excited/nervous/worried for them. I know its a big change and its ok to want them to do things safely - just get the balance right xx