I assume that means the 37130 set with the green loco (BR80) and red and blue coaches?
The BR80 is a great model for kids, no little bits to break off, practically indestructible and looks and runs well.
en.wikipedia.org
In terms of the scale, the loco model is 330mm long and the real (standard gauge) loco is 9.67m so that's 1:29 scale.
The industry tends to use 1:22.5 scale as a synonym for G scale which it isn't as you are finding out, but don't let this worry you for now, just enjoy playing with the train with your grandkids and start planning the rest of your railway empire!