How long do toddlers/pre-schoolers stay in buggies for?

[BettyBi0]

DD will be 2 1/4 when DS arrives. I'm hoping to make do with a sling for the baby and our babyzen yoyo for my 2 yr old for the first bit. I'm wondering what to do after the first bit though.

We live in London and bus/tube it most places as I don't drive. DD buggy naps loads now but I'm wondering how long this will go on for. Is it possible to get away without a double buggy?

My dd is 2 years and 10 months old and we have a 13 week old. When I was pregnant I started to let her walk more often and then when she was about 2.3 years I started leaving the house without it. She likes walking so it worked for her. I knew that there was no way I could get a double buggy as I don't drive so we have to walk or get the bus everywhere. I would fit on the bus and to be honest it's hard enough getting around with a normal buggy around here as the pavements are so small and ppl park over them all the time. We do have hard days though where my toddler wants to hold my hand all the time. She never asks to go in the pram or to be carried but if I hold her hand I have to try and negotiate the buggy with one hand which has resulted in me crashing into things!