You can find some gems on missguided. They have an app which you can track your purchases and returns.
Not all of their clothing is to my style but a good enough majority of it is. I love being able to see the whole outfit when browsing for clothes, like being able to see what shoes go well with the dress I want to buy.
The sales and discount codes appear often enough so you can usually get what you want at a better price.
They have a great range of sizes, styles and a good range of colours.
The delivery is quick, free with click and collect and you won't be overcharged for delivery to your home. The returns are free and easy, too. Just stick the provided returns label on the bag you were sent with your order and you're ready to go.