Respond to the SJPN by pleading “Not Guilty” to both charges. In the “Reasons for pleading Not Guilty” box state that you are willing to plead guilty to the speeding charge providing, and only providing, the “Fail to Provide Driver's Details" (FtP) charge is dropped. This is a tried and tested method to deal with your problem and is almost always successful.
Before the pandemic it was necessary to attend court to do this "deal" because it needs the agreement of the police prosecutor.. During the pandemic courts made every effort to have as few people as possible attend and they began doing this deal under the "Single Justice" procedure without the defendant's attendance. Some courts have carried this procedure on whilst others have reverted to a personal attendance being necessary.