Yes, Povidone-Iodine Products are good as antiseptic, but it is not meant for ingestion. If you have accidentally swallowed a small amount of Betadine during gargling, but you did not receive any symptoms of an allergic reaction, you should be fine but to take caution the next time.
If you have ingested a large amount, there is a risk for iodine toxicity, which can lead to kidney failure, changes in electrolyte concentrations, or other organ failures. Please call 999 or head to the nearest clinic with your Betadine bottle to seek medical attention.