ATMs are widespread. Major credit cards are accepted everywhere. The best place to change money is in post-office branches, which do not charge a commission.
Hotels Pay a porter £1 per bag; gratuity for room staff is at your discretion.
Pubs Not expected unless table service is provided, then £1 for a round of drinks is sufficient. Do not tip at the bar.
Restaurants Service charge often included in the bill. If not, 10% for decent service, up to 15% if exceptional.
Taxis Londoners generally round the fare up to the nearest pound only.