That's all good advice from Eric's Mum.
There are dozens of lawn products in any decent garden centre, or even the supermarkets have some. If you don't want to have to go to the trouble of watering one on, or don't need to if you get lots of rain like we do here on the hills in the north west, you can get a powder or granule one that you just sprinkle on & wait for the rain to water in.
Clearing the thatch off & aerating the lawn can be really hard work if you have a big garden with lots of grass but you can hire things to help quite cheaply by the day from tool hire places, machines a bit like a lawnmower but that scarify & aerate the lawn while you just guide it like a mower.
To be honest, our garden is so big that I don't do it as often as I should, but I just let the geese in to help!
You'll get better advice watching Monty Don on Gardener's World, when it starts again on Friday nights in the spring, than from listening to Richard Jackson.