You may have figured this out by now but the last Narita Express leaves Tokyo at 20.03 (and Shinagawa at 19.50), so you'll have to leave Kyoto at 17.16 or 17.23 in order to catch this train on 26th. It's unfortunate that you have to stay near NRT on the night of 26th. Since you are likely to be staying in Narita itself rather than at the airport, you can take a later Keisei Evening Liner train to Keisei Narita station from Keisei Ueno or Nippori station. This should give you up to one hour extra in Kyoto but it's not as convenient as changing from the Shinkansen to Narita Express at Shinagawa.