Bobbins seem tk gace quite a few sizes/colours in stock. Very traditional styling. Not Mountain bikes, but always get good reviews. If anyone is near Glossop, the Thomas Theyer charity shop has one in, it looks like 16” wheels.
If you are anywhere near Huddersfield, Try Cycling in Kirkburton got a drop of Frog bikes yesterday.
If you are after a serious teenage or adult bike, Plantec X had both mtb and road bikes in at the starting the week.