Write a Programme Narrative

You are an experienced UK construction Planning Engineer. Write a programme narrative to accompany a baseline construction programme based on the following:

Project: [PROJECT NAME AND DESCRIPTION, e.g., New-build 120-bed care home, steel frame, 3 storeys plus basement]
Client: [CLIENT NAME]
Contract Form: [CONTRACT FORM, e.g., NEC4 ECC Option A]
Contract Duration: [DURATION, e.g., 78 weeks]
Start on Site Date: [DATE]
Completion Date: [DATE]

Key Project Information:
- Gross Internal Floor Area: [GIFA]
- Number of storeys / blocks: [DETAILS]
- Structural frame type: [e.g., Steel frame / RC frame / Timber frame]
- Key constraints: [LIST, e.g., Live hospital environment adjacent, restricted working hours weekends, phased handover required]
- Sectional completion requirements: [IF ANY]

Key Milestones:
1. [MILESTONE 1 AND TARGET DATE]
2. [MILESTONE 2 AND TARGET DATE]
3. [MILESTONE 3 AND TARGET DATE]
[Add as required]

Programme Assumptions:
- Working hours: [e.g., Mon-Fri 07:30-18:00, Sat 08:00-13:00]
- Holiday shutdowns: [e.g., 2 weeks Christmas, 1 week Easter]
- Lead-in times assumed for key packages: [LIST, e.g., Steelwork 12 weeks, Cladding 14 weeks, Lifts 20 weeks]
- Weather allowance: [e.g., 2 days per month Nov-Feb]

Structure the narrative as:
1. Introduction and project overview
2. Programme overview (start, finish, duration, calendar)
3. Enabling works and site establishment
4. Substructure phase description
5. Superstructure phase description
6. Building envelope and weathertightness
7. Internal fit-out sequence (describe floor-by-floor or zone-by-zone approach)
8. External works
9. Commissioning, testing, and handover
10. Critical path description (identify the critical path through the programme and explain why)
11. Key milestones summary table
12. Programme assumptions and exclusions
13. Key risks to programme

Write in a professional technical style suitable for formal programme submissions.