Check the label on the back of the HG612. If it has large '3B' (or '2B') and came with a white mains power adapter, you should be fine.
As far as I can recall, there were two issues. One was very earliest HG612 overheating particularly if they were not wall mounted and so could possibly catch fire. The second was a separate electrical safety issue with the black coloured power adaptors.
ex-Plusnet (ADSL, FTTC) 2008-2023. now BT (FTTP) 2023-