For me what would make the high street more attractive to shoppers would be to ban cars and lorries from them, beautify them with hedges and whatnot, make them actually pleasant places to be. My nearest high street is basically a ghastly through road full of constant maintenance work being done on the road surfaces or utilities. It's just not a nice place to be around.
This, really. Our local high street is in the doldrums (even the Coop and Subway have closed). Parking seems to get a lot of the blame, though I'm unclear who drives to their local high street – surely the point is that it's local. If people get in their cars, they're likely to drive somewhere else. There's no point competing with that, there's never going to be acres of parking and a warehouse full of stock (and even those venues lose out to the internet). Really, you need places that people want to go, that don't replicate what is cheaper and more convenient elsewhere. So, cafes, boutiques, restaurants etc. There's endless studies to back this up, but to be honest, they could just go look at a successful high street and it won't be a main road. That just takes people elsewhere and, if they stop, it'll be lottery tickets and fried chicken, and that's the high street you'll get, punctuated by charity stores. At which point, why go? The ambience of the occasional drunk and the thrill of watching shoplifting teens do a runner? Or an evening out watching underaged kids drink the booze they're bought from the convenience store followed by a kebab?
But nothing in the local development plan challenges that (though they at least acknowledge the principle that building a high street around traffic won't work, while being unwilling to do anything to change that). They won't stop through traffic (there's a bypass anyway) or pedestrianise, and they're adding yet another supermarket, so basically it's a slip road to the weekly shop, and even less reason to hang around.
At least we can just get the train into London, which is shame, we'd like to do more stuff locally.