I have looked at lulu lemon and I’m a size 14/16 and I would be a 10/12 and I have a smaller waist/hips than her. Obviously I need to try them on before I buy. I go up a size a certain week of the month too which needs to be taken into consideration as the leggings are €€€
I brought leggings and shorts at lulu lemon and had to go down to 8/10, I removed the tags so I am not sure what the size is actually (tags are always so itchy). I am a similar shape to Brogs and usually fit the sizes L/XL, 42, and 14/16, and was generally surprised that I had to go down that many sizes! Not sure if the batch for my tights and shorts were a bit big but I would totally recommend you try them on in real life. Just for your information, the tights are skintight and comfortable but so veins and small bumps on the subsurface will be visible. I brought green tights and black bicycle shorts so I am not sure if all thingst is like that, but then again thanks to genetics the veins on my legs are sometimes big and noticeable.
I wonder if lulu lemon has a sale on black Friday/black week, if they do then you try some items on beforehand and order them on sale. I dare not say what I paid in-store, I cried a bit that day.