My vet didn't test with a woods lamp, she just looked him over and said she was confident it was ringworm - he has one bald patch under his jaw and two round bald patches on his right elbow. To be fair, the shelter vet had tested for ringworm and it had come up positive - I think they were trying to downplay it on the phone.
My vet also gave me a Milbemax tablet, and examined the pup - temp, heart, abdomen, teeth, ears - his ears were dirty so she gave them a good clean, which he tolerated with good grace. No sign of infection or mites, just scruffy - nice and clean now. She also gave me a script for the chemist, just in case the remedy wasn't OTC.
Testament to how beautiful the pup behaved and how sorry his weight is - the vet charged me the cost of the Milbemax tablet and sent me on my way.