I have just purchased what might be the ultimate save money and save the planet device. A Thermos bottle. Have you found your own way of saving while limiting your use of disposable containers like coffee mugs?
My Thermos bottle keeps coffee piping hot, has its own little cup and comes from Hema in the Tottenham Court Road - next to Cath Kidson. It's small and neat too - and tough, made of brushed stainless steel. The 500ml size (24.5 cm high, 7cm diameter) costs £12.50. The shop also has a 1L which is just a little bigger and costs £15.
PS: yesterday I posted about how helpful I find Deliveroo for providing proper meals not too expensively (and with a surprisingly large saving of time since there's no shopping, cooking or washing up involved). Lots of plastic packing however: I'd like to come up with some ideas for that . . . again, you're welcome to join in.