My ferritin levels are 233ug/l (range 12-300) but is this too high?
Your result is three quarters of the way through the reference range, which is hardly "sky-high".
Whether or not a result is sky-high or not depends on the reference range, and the ranges differ from lab to lab.
One of the common reference ranges for ferritin is 13 - 150. If your result had been 233 with this reference range then your result would have been too high, but it isn't, so you are okay.
I would suggest that you don't take any supplements with iron in because you don't need it.
Another thing to take into account is that the body stores ferritin when there is inflammation in the body. Inflammation is common and can occur in all sorts of places e.g. joints/muscles, gut, lungs.