All of the newer generation trains I've been on so far have at-seat plugs for 240v and USB (and wi-fi), so you can easily charge your e-bike battery, tablet and phone, browse this Pedelecs forum, drink a beer and eat a bacon sandwich from the cafe-bar... all at the same time!
Greater Anglia this year replaced nearly all their trains with new Class 745/755 FLIRTs... but there's only TWO bike spaces on the whole train (the old IC Class 90's had tons of bike space), so bikes now need to be pre-booked even though carriage is still free. The biggest issue is maybe that Greater Anglia's longest distance journey London to Norwich is as quick as 90 minutes... not much of a chance to charge anything! Even the new East Coast Azuma's take only 4.5 hours London to Edinburgh, so charging an e-bike battery on a typical journey will be a nonsense for most people.
Of course if you live oop north, you're probably dreaming of even a humble mains socket to charge anything as you're still largely stuffed with decrepit 40 year-old Pacers and Sprinters!