Accommodation thresholds
Cap nightly rate at £150-£200/person depending on city. Above that requires line-manager approval. Cap nightly rate for solo travel at £120 (forces use of value accommodation; serviced houses naturally come in under for groups).
Meal allowances
£35-£45/day for full-day site work including evening meal. Receipts required above £15 single item. Alcohol not reimbursed (or capped at £5/day if you must).
Travel
Standard class rail. Off-peak where the project schedule allows. Hire car only where public transport adds 90+ minutes per day. Mileage at 45p/mile for first 10k miles per year.