so is it possible to build a small talkie walkie similar a bit to the one used in the racing world ?
No in your country you are not permitted.
what about the toys i guess it's very low frequency
You guess wrong.
doesn't cover much more than 20meters or something
Range is not a consideration for most countries, as yours and mine, it is the act of making and using an unlicensed transmitter. Again there are bands for type approved equipment and that includes toys.