In the United Kingdom, the culture of tipping is less prevalent than in the USA. Employers are now legally obligated to pass on their tips to employees.
In most UK hotels it is not customary for guests to tip, except in 4-5 star hotels where you can add 10% to your total bill. If you have booked a sightseeing tour you can reward your guide with 10-15% of the price of the experience, or more for a volunteer. Taxi drivers don't expect a tip, but you canAdd 10% of a fare (in cash, card or via apps like Uber)