I'm trying to learn how to drive a touring car properly and noticed a small deadzone in the steering. It is about 7-10 degrees each way, not much looking at it bit 14-10 degrees seems a lot to me, but I'm a total beginner. Does every transmitter have a small deadzone? I'm using a Flysky FS-GT3B.

Did you replace the stock steering wheel? I have seen some kits out there such as Integy that offers custom wheels with adapters that don't always fit properly, I have used electrical tape as shims to fill the gap in the adapter to eliminate the play in the steering wheel. Have you also added exponential steering to your radio? That can also create a deadzone in the center as well. 20° of dead travel is not normal

Standard wheel and expo at zero, maybe because it's a £35 Chinese radio, it feels good quality and has good features but obviously cheap parts. Maybe this year Father Christmas will bring me a Sanwa.

I was gonna suggest messing with the Expo as well, but, since you got that outta the way, I'd move on and test the steering using the Tx's trigger (swap inputs on the receiver). If you think the FS-GT3B has good quality, than you're in for a treat with a Sanwa .