Any mum should have at least a couple of these amazing toddler training pants. They are called Mom and Bab. You can find them on Amazon.
They are pretty, made of cotton, they fit and look like the real, grown up ones but have a waterproof inner layer that helps containing small accidents. They are also reasonably priced (GBP 8.95 for a pack of 2) and of good quality. They will last for ages. My daughter was very proud to be wearing them especially because she did not have her trousers all wet in case of a small leak.
Please note that sizing is a bit difficult to interpret. I bought a size medium for my very tall 2 years old and they were perfect. On Amazon you can find them through a seller called Fab4Babystars. If you email or call them up they tend to have more designs in stock and can give you advise about sizing.