The government is proposing to put all these together in a digital wallet, so this system will hold all the information they currently have about you in these systems and more in one place, making it a more attractive target for hackers. They are already talking about using it for employment and rent checks, which will add to the information they hold about you in this one database. It could easily be used to track everyday interactions such as paying bills, shopping and voting. After all, if we've got digital ID, why shouldn't it be used for age checks, proving eligibility to vote, etc.
The digital ID system will hold more information on you than any single system holds at the moment. As time goes on, it is likely to hold lots of information the government don't currently have access to at all. They don't currently know whether you voted in the last election. If your digital ID has to be scanned to prove your eligibility, they will know. And if your digital ID starts being used for age checks, they will know every time you buy alcohol or other age-restricted goods, or visit websites that require age checks.
Some 4 million immigrants are already forced to use digital eVisas. This system has been beset with problems, with authorised immigrants being stranded at airports when their eVisas failed, GPs wrongly rejecting credentials and refugees being unable to connect their passports to their eVisas, meaning they could not set up bank accounts or rent housing.
When ID cards were mandatory in the 1950s, some police officers abused their powers by arbitrarily demanding people produce their ID cards and rounding up and questioning girls in the West End of London who could not prove their identity. That was a long time ago, but even today police officers, and occasionally staff employed by the police, regularly access the Police National Computer illegally for unauthorised purposes.
Those kinds of issue may not worry you if they don't affect you, but they will certainly worry you if you are forced to carry a digital ID and experience similar issues. To expect a government digital ID system to be secure and not be vulnerable to this kind of problem is a triumph of hope over experience.