I had a total thyroidectomy and now take thyroxine. Must I avoid eating raw broc!

You really don't have to avoid it. Raw broccoli is a goitrogen and goitrogens decrease the uptake of iodine in the thyroid. You don't have a thyroid anymore, so that is really a non-issue. Cooking the broccoli deactivates the goitrogenic properties, but anyone can eat raw broccoli. Moderation is key.

thyroid cancer patient

Raw brocolli can interfere with the thyroxine producing function in the thyroid gland. Well, you no longer have a thyroid gland!! So you can eat as much raw brocolli as you like.

You'll be getting all the thyroxine your body needs from medication.

The Internet is full of misleading information. Go by what your Doctor says. Why would you want to eat raw brocolli? Thats a first for me.
If you look at the leaflet with your pills it will tell you what to avoid on there.

yes, your doc is right