The Class 93 is not going to be anywhere near powerful enough in non-electric mode for those requirements. A 93 wheezing over the Pennines or the South Devon banks with just its engine (and a chunk of that power used for train supply) cos the Duracells are flat ain't going to cut it.
I immagine the power will be blended. It. may well and we will only find out when the trains are up and running.
Blended power will basically come about that when on steep grades like the Devon banks the battery will make up the power difference the smaller engine lacks. When braking such as a car then regen will top the battery up. What most people don't spot is that it's quite possible that when going down hill or on the flat and at line speed the locomotive can run the diesal engine to charge the batteries too and I immangine it would make a Tesla rapid charger look rather puny.
Obviously this is all speculation but seems entirely reasonable. We have to stop thinking that on Diesal it only produces power from that source, just like we have to stop thinking when it's at line speed, stopped at a red, going through slow speed track layouts that the engine is throttled back when it can be at full tilt charging the battery up.