I believe that most have been mentioned in some capacity above, but just for completeness:
Transpennine Express: 13 x Class 68+5-car CAF Mark 5 rakes (Deliveries commenced 2018)
Northern: 25 x 2-car CAF Civity Class 195 (Deliveries commenced 2018)
Northern: 33 x 3-car CAF Civity Class 195 (Deliveries commenced 2018, additional 3 units ordered 11/2018)
West Midlands Trains: 12 x 2-car CAF Civity Class 196 (Into service by 12/2020)
West Midlands Trains: 14 x 4-car CAF Civity Class 196 (Into service by 12/2020)
Transport for Wales: 51 x 2-car CAF Civity (Into service Q3 2021 – Q1 2023)
Transport for Wales: 26 x 3-car CAF Civity (Into service Q3 2021 – Q1 2023)
As well as dual mode units that'll probably spend reasonable amounts of time on diesel power:
Transport for Wales: 7 x 3-car Tri-mode Stadler FLIRT (Into service Q1 2021 – Q4 2023, for Rhymney/Coryton - Penarth/Barry Island)
Transport for Wales: 17 x 4-car Tri-mode Stadler FLIRT (Into service Q1 2021 – Q4 2023, for Rhymney/Coryton - Penarth/Barry Island)
Transport for Wales: 11 x 4-car Bi-mode Stadler FLIRT (Into service Q2 2022 – Q1 2023, for Maesteg – Cardiff – Ebbw Vale/Cheltenham)
Greater Anglia: 14 x 3-car Bi-mode Stadler FLIRT Class 755
Greater Anglia: 24 x 4-car Bi-mode Stadler FLIRT Class 755 (Deliveries commenced late 2018)
And for absolute completeness, if you’re including the Hitachi Class 800s and 802s (I’ll exclude the 801s as they only have one diesel engine purely intended to provde ‘limp home’ capability):
GWR: 36 x 5-car Class 800/0 (All delivered and in service)
LNER: 13 x 9-car Class 800/1
LNER: 10 x 5-car Class 800/2
GWR: 21 x 9-car Class 800/3 (Ordered as electric only class 801/0, all now delivered as 800/3s)
GWR: 22 x 5-car Class 802/0 (Deliveries ongoing)
GWR: 14 x 9-car Class 802/1 (Deliveries ongoing)
TPE: 19 x 5-car Class 802/2 (First 2 units undergoing testing)
Hull Trains: 5 x 5-car Class 802/3 (Due into service by 2020)