Is Yule (Christmas) - Orignally Thors feastival?

I ume you live in Britain. The issue i have with your question is the word "originally". Certainly after the Angles, Saxons, Frisians and Jutes invaded this island, they were Asatru and celebrated some kind of winter solstice festival, but they weren't the first people here. The Romans had Saturnalia, the British Celts before them had some other solstice festival and clearly the builders of Stonehenge considered it to be important thousands of years before. So, yes, it was a Nordic festival at some point but it's been a lot of other things too.