SueHi Bonnie, If your husband has a work contract for at least 6 months and your son is accepted in school over here, you will all be covered under the NHS for free healthcare. However, if you have private cover, you still may prefer to use this. It depends on the age of a child and their control as to whether they are routinely seen 3, 4 or 6 monthly under the NHS. With private insurance, you are the one making this decision!
As to Arimidex, it is used occassionally over here and considering your son is already on this, I would doubt any endocrinologist would change his medication, if he is doing well. Please feel free to contact me if your husband takes the job and I will ensure you are put in touch with a paediatric endocrinologist who meets your needs. I will also try and help if you need any other information and advice. Good luck!