Radioactive Iodine Treatment

I’m looking for some comments and help with the above, please.
I’ve had surgery (Mastectomy with immediate LD Recon.), 3 x FEC, 3 x Taxotere, 25 blasts of Radio, Tamoxifen for 8 months, Ovaries and tubes removed, and now I’m on Arimidex and halfway through my year of Herceptin.
In October last, I was diagnosed with an overactive thyroid. After more scans and a CT, I’ve been told I’ve got a “hot” nodule and will be given radioactive iodine to get rid of it. (First I’m having a FNA on Friday, “…given your history”)
Finally, I’m getting to the point! Has anyone else had BC first and then this treatment? There appear to be a number who have had it the other way round, but I’ve got concerns about this treatment’s effect on Herceptin, Arimidex, and my poor abused immune system.
I would love to hear from anyone who has any pointers or some questions that I should ask either the Oncologist or the Endocrinologist!