At the west Gate of Temple of Heaven, bus 827 can take you to the summer Palace directly. There are restaurants in the Summer Palace, but I never go one. 40 minutes to get there, I think. I think it is better to get there in the morning. Wel, you can take subway if you get out of the Temple of Heaven from the East Gate, however, need to transfer from Line 5 - Line 2 - Line 4.