You'll be in good company at Customer-First Forum, here is a sample list of attendees:

Both lists have been alphabetised and so do not correspond to each other.

Companies

Absolute Intelligence
Anglian Water
Baringa
Cadent
Capita
Centre for Sustainable Energy
Centrica
CCW
Centre for Sustainable Energy
Citizens Advice
E.ON UK
EDF Energy
Elexon
Evouchers
Energy Systems Catapult
Engage Consulting Ltd
Evouchers
Galliford Try Construction Ltd
Good Energy
Hope4u
Itineris
Jersey Water
John Lewis 
Journey4
Kier Natural Resource Nuclear and Networks
LEMA (Local Energy Markets Alliance
Marston Holdings
Medallia
National Gas
National Support Network
NESO
NFON
NHS Shared Business Services
Octopus
Odigo
Ofgem
Ofwat
OLT Limited
Powerverse
Quadient
Sabio
Scope
Scottish and Southern Electricity Networks
ScottishPower
SES Water
Severn Trent
Sirio
Smart Energy GB
Sopra Steria
South East Water
Southern Water
SP ENW
SSE Airtricity
Talan
​​​​​​​Thames Water
Transform UK Ltd
Trust Alliance Group
UK Power Networks
United Utilities
Utilita
Utilita Giving
Verint
Vyntelligence
Wales & West Utilities
Wessex Water 
Wipro
WNS
Yorkshire Water

Job titles

Applied Ai Strategist
Business Development Director UK
Business Development Manager
CEO
Chief Customer and Digital Officer
Chief Customer Contact Officer
Chief Customer Officer
Chief Executive
Chief Executive Officer
Chief Financial Officer
Chief Home Services Officer
Client Solutions Director
Commercial Director
Commercial Manager
Communications & Customer Senior Manager
Connections Customer Manager
Consulting Partner - Utilities
Consumer Strategy Lead
Consumer Strategy Manager
Corporate partnerships lead - energy
Customer Experience Manager
Customer Strategy Manager
Customer Service Director
CX Solutions Specialist
Delivery Management
Deputy Director of Marketing
Director
Director of Client Success & CX
Director of Customer Solutions
Director of Customer Experience & Operations 
Director of Research and Analysis
Director of Settlement Services
Director of Water & Energy
Executive Director
Former Head of Customer
Founder and Director
Future Networks Innovation Project Manager
Grid Policy Specialist
Growth & Impact Lead
Head of AI Policy
Head of Business Development
Head of CIOS
Head of Customer Excellence
Head of Customer Experience (East of England & North London)
Head of Customer Insight 
Head of Customer Operations
Head of Customer Operations and Markets
Head of Customer Service
Head of Industry Relations
Head of IT
Head of Marketing - UK & Ireland
Head of Partnerships & Innovation
Head of Product
Head of Sales
Head of UK Strategy
Head of Utilities
Manager
Managing Director
Operational Customer Service Manager
Principal Policy Manager
Principal Sector Manager
Sales Director
Senior Advisor
Senior Advisor – AI Strategy
Senior Energy Policy Advisor
Senior Client Partner
Senior Consultant
Senior Director, Communications and Engagement
Senior Energy Policy Advisor
Senior Leader - Engagement
Senior Manager
senior manager of industry change
Senior Manager, Regional Marketing EMEA
Senior Policy Analyst
Service Delivery Director
Smart Metering Lead
Stakeholder Engagement & Audience Lead
Stakeholder Engagement Lead
Stakeholder Engagement Manager
Strategic Account Executive
Team Lead, Sales Development
Technical Project Manager