Plus size workwear - going outside my comfort zone

This week is a tricky one. I have a reasonably wide comfort zone, and I tend to buy all my clothes inside it. Because well, if I don't like it and feel comfortable in it.. I don't buy it.

Therefore for this week's challenge I have slightly cheated and worn something that I would never have thought to buy. I give you...Primark bodycon dress. Is this suitable for work? Yes, perhaps with a blazer but it is black and dressy enough and not an overly night-time look. Love the pattern and surprisingly ok with the complete clinginess.

Did I buy it? I was sorely tempted, but this is an size 18. If the size 20 had been in store I would bought it, especially as it is only £10. Why do all the size 20's disappear so quickly - is this the most annoying symptom of the obesity epidemic everyone keeps talking about???