I will be arriving on BA into terminal 5 and departing for Toronto 1:50min later. I will have a 3 year old in tow.

1) how much will I need to rush to make this work?
2) what happens if we miss it, not because the flight is delayed, but because 3 year olds just can’t walk very fast?
3] I understand I wi,l have to collect my bags and recheck them. Will there be baggage trollies at that point? I don’t know how else I will be able to carry everything (travelling alone with kid)