Whenever you do a deal you have a bid and ask. The bid is the top price a buyer is willing to pay and the ask is the top price the seller hopes to get, and between these two a price is gets agreed.
The broker makes a living off the difference (the spread).
When you are selling the return is based on roughly what you hope to get for it in this case around 8.8p
Its kind of like part-exchanging a car and the dealer goes we’ll give you £800 for that banger, and you want at least a grand so we’ll call it £900 
Next person comes along this car is £1200 to buy, and the buyer says well I’ll give you £1100 for it, no says the dealer but what about £1150? Ok, sold! So the dealer made a swift £250 from simply moving the car from one person to another.
T212 isn’t adding their fees via it to make money, they make them through CFD instead.
In summary always look at the sell price when selling and the make sure the return is green. With volatile stocks and dealing with small amounts and small percentage either way and it can be huge amounts difference.
Edit:
These might be better to explain it.