Hi Lala,
Sorry to hear about your Corgi's diagnosis.
Your question made me think of an article I read several months ago about non-surgical solutions. I am not a vet, and neither is the author of the article a vet. However, they did take a dog though fairly intensive bed-rest alternative and the dog improved without surgery. The article is heavily biased against surgery, but might be worth a read just so you know you might have an option.
Link:
Dog ACL CCL Ligament Recovery Without Surgery No TPLO