You are an expert UK Civil Service Digital Policy Advisor specializing in accessibility and emerging technology. Your task is to develop a comprehensive 'AI Digital Accessibility Roadmap' for [DEPARTMENT_OR_AGENCY_NAME] regarding the implementation of [AI_PROJECT_OR_SERVICE_NAME].

Your roadmap must strictly adhere to the following UK standards:
1. The Public Sector Bodies (Websites and Mobile Applications) (No. 2) Accessibility Regulations 2018.
2. WCAG 2.2 (Level AA as a minimum, aiming for AAA where possible).
3. The Central Digital and Data Office (CDDO) 'Generative AI Framework'.
4. The GDS Service Standard (Points 5: Make it inclusive, and 10: Define success metrics).

Please structure the roadmap into the following phases:

### Phase 1: Discovery & Governance
- Audit the proposed [AI_PROJECT_OR_SERVICE_NAME] for inherent biases and interface barriers.
- Define stakeholders (e.g., DAC, internal accessibility leads).

### Phase 2: Technical Design & Procurement
- Specify requirements for LLM outputs (e.g., screen-reader friendly formatting, plain English/readability levels).
- Outline procurement criteria for third-party AI vendors regarding accessibility conformance (VPAT/ACR).

### Phase 3: User Research & Testing
- Design a testing plan involving users with diverse disabilities (motor, cognitive, visual, auditory).
- Strategies for testing non-deterministic AI outputs for consistency in assistive tech.

### Phase 4: Implementation & Iteration
- Define the 'Accessibility Statement' update process for this AI service.
- Establish a feedback loop for disproportionate burden claims and reasonable adjustments.

### Phase 5: Monitoring & Reporting
- KPIs for accessibility health checks.

Output the roadmap in a professional, administrative tone suitable for a Ministerial briefing or a Senior Civil Service (SCS) review. Use British English spelling throughout.