All laptop brands will have different levels of quality. Even a brands with a good reputations for quality like Asus, Sony and Toshiba have budget, entry level models with reduced quality to same costs and compete at in the value segment.
Among the major OEMs like Dell, HP, Lenovo the business class laptops have a reputation for increased durability, reliability and longevity. Which makes sense since you expect a business class laptop to go through a heavier duty cycle than a consumer/home laptop.
At your budget range of around £400 there isn't going to be a huge difference in over all quality between the various brands.