Bedfordshire's easy - the MML north of Bedford, though that's currently being wired for the Corby services, longer distance i.e. Leicester, Nottingham will remain in the hands of diesel / bi modes for the foreseeable. But there isn't another stop in Beds north of Bedford.
The only other bit in Beds which is non-electrified is the Marston Vale (Bedford - Bletchley) - the line's only 16 miles in total and I'd "guess" the amount of that in Beds is about 10 miles.
Bedfordshire will be well over 90%.
In terms of the GA network you're looking at the following as diesel:
Norwich - Sheringham
Norwich - Great Yarmouth
Norwich - Lowestoft
Norwich - Ely
Ipswich - Lowestoft + Westerfield - Felixstowe
Stowmarket - Cambridge
Ely - Peterborough
Marks Tey - Sudbury
I suspect that the majority (i.e. over 50%) is wired - because you've got London - Colchester - Ipswich - Norwich wired, London - Kings Lynn wired all the suburban branches in Herts and Essex wired (Sudbury is in Suffolk, so not included there).
Don't forget there is some running 'under the wires' for example Cambridge - Ipswich services do because operationally it makes more sense for them to run through to Ipswich than turn back at Stowmarket where the Cambridge line joins the electrified Norwich mainline.
