Good stuff, are your legs feeling stronger?
I ride around Christchurch with my kids in the trailer. Get your fitness up, then start doing short trips with just one child. And then once your comfortably dragging on kid around throw in the second one.
The only thing you have to watch out for with a trailer is that you can't squeeze past cars as easily, so sometimes you just have to wait in line, rather than squeezing your way to the front of the que.
FWIW, at age five your kids are probably getting too big for the cheap trailers, so I'd recommend you try before you buy.