Building plastic scale models is still a big thing, (ditto, aircraft, ships, military eqpmnt, railways etc etc). There are lots of very good websites covering all these topics and today's models and modellers are truly excellent. Have a look here for UK-based site on cars/motorbikes.
www.spc.org.uk/
Yes, Airfix has gone but they left an enormous legacy. Look up Tamiya, or Hasegawa or, if you want to see the best in car modelling - at 1/8 scale, go Googling for Pocher at :
www.scaleautoworks.com/
Enjoy, there's lots of us still builfing and many younger folk starting, but it's a whole lot more sophisticated now and having just retired I count myself as back to beginner class.