When I bought first bikes for my boys, I didn't want them too babyish. It's actually quite a challenge to find a small bike that isn't Paw Patrol or Peppa Pig.
Argos sell Huffy Bikes, and have them half price just now. These are much more grown up looking and are VERY highly rated.
The cheapest Huffy Bikes are the 12" ones. These come with removable stabilisers and are aimed at children that are just learning to ride. Choose between Blue*
. They are now only £49.99 each, reduced from £99.99.
You can Reserve and Collect your Huffy Bike for FREE from an Argos store near you or pay £3.95 to have it delivered to your front door.