Do pillowcases come included at this price?
Yes, on every set here. One pillowcase with a single, two with double and above. The price you see is for the whole set, not the cover on its own.
Is cheap bedding scratchy?
Modern polycotton and microfibre are not, which is the honest answer. What you give up at this price is the weight and the breathability of pure cotton, not softness. If you sleep hot, spend a little more on cotton bedding and you will notice the difference.
How long will it last?
Washed weekly, expect a couple of years of good service before the colour starts to go. That is reasonable for the money, and it is why this range suits a room where the look is going to change anyway.
Do they need ironing?
Mostly no. Polyester and microfibre come out of the wash close to flat, and a lot of the range is formally non iron. Have a look at non iron bedding if that is the deciding factor.
What sizes do you do under £10?
Single, double and king across most of the range, with fewer designs in super king, since the bigger the cover the harder it is to keep under a tenner. Single has the widest choice.