Penny's school, I am not sure the specific location but it sounds pretty close to Penny's house because sometimes she walks to a restaurant called BJ's that is on the dock, with her friends, and then walks back to her place or sometimes she walks there with Elliot. Penny's house which is located in a City in Britain and it is connected to Elliot's house because him and Penny are only a door away. Finally, The wedding shop which does not have a specific location but it is near other shops and I think it is close to Penny's house, the wedding shop is a shop owned by Penny and her Mom (mostly her mom but Penny just helps with it)
The time in my book is December and I think it snows in December there. I imagine it to be like below zero and really foggy (really cloudy). It doesn't really explain that its cold in the book. The characters are not wearing cloths that someone would wear if it was could, they wear dresses, jeans and a top, clothing like that. So Im not really sure if its sunny or snowy but I imagine it being snowy in December there.