Just in case your mind wasn't set on getting a backpack... I am from England and have traveled regularly by myself with my children since my eldest was about 18 months. I have used a backpack, but I have actually found it much easier just to take one of those small umbrella strollers. If you will be flying, there is all the standing around waiting at the airport, and the back pack gets heavy after a while, not to mention all the hassle of getting in and getting out as you have to go through the security checks. You can put your hand luggage in a light weight case which is easy to pull with one hand while you push the stroller with the other, or put your hand luggage in a small back pack. The other thing I like about having a stroller is that you can drape your coats over it as it is usually hot in the airport. The good thing about having a small folding stroller is that the cabin crew have occasionally let me take it onto the aircraft myself, and even if the flight is heavily booked with not much room, they let you take it all the way to the aircraft then they store it for you and bring it right to the door when you get off.
My personal choice is to always go with the stroller - until your second comes along, then it is one in the stroller AND one in the back-pack.
Hope you have a good trip.
L. P