@gogohm
I walked to school 40 mins each way from 11-16, the only waterproof thing I had was an umbrella (school coats were wool). We all survived. If you can't afford a £5 umbrella and £20 jacket for your kids (cheaper from charity shop) I doubt you can afford petrol
But you generally need more than that.
Around here an umbrella is pointless as we're by the coast so it's windy and they just blow inside out and break.
So you need a good waterproof coat (which costs more than £20 if you want it properly waterproof), waterproof trousers and waterproof shoes or wellies. So probably £40-50 per child.
Not too expensive, but considering how quickly kids grow, they will need replacing fairly regularly.
Plus most schools (especially secondaries) have nowhere to store any of that stuff, so you have to cart it around in a plastic bag in your backpack all day, meaning it doesn't dry, and meaning when you go home, you either have to get wet, or put on wet, damp, cold clothes which won't keep you dry anyway.
I mean, yes, it's doable but it's not exactly pleasant. And if you can't afford the waterproofs, or your kids won't wear them (and how many teenagers do you know who are going to wear full waterproofs to get to school), it's miserable walking in torrential rain and sitting around all day in wet clothes with wet socks and shoes.