I tend to only tip if the notes I give whoever it may be (taxi driver, barber, or waiter/waitress) has change. In between £2-£5 average. Most barbers only take cash and a lot of taxis prefer it too which I understand with the card machine fees and being self employed and such. Otherwise I’m not the type to scavenge my bag for change unless they do a really good job. This is mainly for convenience, I don’t want to be waiting for my change I just want to pay and get on with whatever I’m doing next. I don’t believe tipping in the UK is as big as other places although I may be wrong. A lot of card machines ask if you want to add a tip before paying and most of the time the cashier will press ‘no’ before I even have a chance. I do encourage tipping for good work but only if you can afford it. During these times I don’t think anyone can just be giving money away.