I'm a big advocate of using flash in indoor photography to make sure you get the photo. I hate the disappointment of reviewing afterwards and finding blur in the photos which, when corrected in Photoshop still doesn't look right. Visiting Leicester yesterday we were at my Grandparent's house which gets a good amount of natural light in through the conservatory and managed to get some excellent results without using flash. Indeed, this photo, when put through Photoshop for colours/levels/contrast didn't require anything at all - essentially as it came off the camera. The same also applied to this photo. Hopefully with the sun making more of an appearance now, I'll be able to play with natural light a little bit more.