Decathlon do some good cheap stuff if you have one nearby.
Walking trousers, like cycling shorts don’t have seams in places that rub, they’re also made of layers, mine have an inner, a mid layer and an outer which keeps them warm most of the year and cool in summer.
Above the cheapest level the Karrimoor boots at sports direct are pretty good. I’ve walked through several soles and never had the upper or waterproof membrane go first.
Other than that, map, compass, whistle and seasonally appropriate emergency gear. In summer that could just be an emergency bivi bag, in winter at least one extra layer top and bottom, dry hats and gloves.