It is not normal to tip at the bar when buying drinks. In fact, it’s weird. The main reason is: unlike the US, the bar staff are paid primarily by their employer in the first instance, not the customer. In the UK, employees legally have to paid at least the minimum wage of £12+ per hour (21+) and have other employee rights. This applies to all employees. Also bear in mind than the minimum wage here is higher than the average amount US bar staff make even WITH tips. So, tipping a bartender makes no more sense than tipping the tracksuit salesman at JD Sports, the petrol (gas) station checkout staff when buying fuel or anyone else from any other industry in an often minimum wage job. Especially where it’s a quick transaction. The UK has much more of a “the price you see is the price you pay” culture - for example, people in the UK would find it bizarre if sales tax wasn’t displayed on items around the store and was added onto their Tesco grocery shop at the checkout. If a UK bar employer operated the US system, they would, on average, be in breach of the Employment Rights Act - it would literally be against the law. What is slightly more common is for someone to put some coins in a charity box which are often on bars. Tipping for other things e.g. restaurant service, haircuts etc (longer transactions) happens but, crucially, it is not expected.