Thanks for all the input. I would call to check except that I'm pretty sure that the answer would be as Eternaltransit has linked to.

My (badly phrased) question was really about the amount of oxidising material in the solution. There may be Fluorine in your tooth paste or mouthwash for example, albeit in tiny quantities, it doesn't result in the toothpaste being banned.

What I want to take is water with a small amount of hydrogen peroxide in it. That alone may indeed make it a banned substance but everything that I can find online doesn't make it clear. Would it still be banned if the percentage was 0.6% H2O2 for example, or 0.006%?

I guess I was hoping that someone would direct me to a reputable source that said "Yes, as long as the % of H2O2 doesnt exceed y"

I shall err on the side of caution and leave it at home!