I am currently in England and need to e-file my tax return. It's still October 15 in the US but TurboTax won't let me efile.

It goes by the time zone and date that YOU (and your computer) are in.    As midnight rolls through the time zones in continental U.S. others will miss the deadline  if they have not filed by midnight in their time zones.  Now you will need to print sign and mail it.  Use a service that will track it so you will know it was received.

You can try resetting your computer to Pacific time and try again.  Not sure it will work.