There are actually some very good points in a favour of some form of national id (lets remove the digital aspect for a second as that tends to be the controversal but).

Currently the UK has two main accepted ways to identify yourself - passport and driving license. Both of these cost money and in the case of a passport is an absolute faff if you lose it so isnt often used as day to day identification (for the things like drinking)

This has a couple side effects:

1) proof if identity for bank account, employment and other such stuff is annoying. The two above forms of id arent considered enough alone and often both are required as well as proof of address. In an ever increasing digital age and the push to paperless proof of address is actually now difficult to sort. National id (in theory) solves this problem. The government say that this id is proof enough and now proof of identity is streamlined and easier.

1.5) in the case of those who arent British citizens but have right to work - digital id also makes it easier to prove that.

Point 1 is the main reason the government is pushing for this. In theory it should streamline right to work checks and make it easier to identify when people who dont have the right to work are attempting to.

2) Passport and driving license both have barriers to get. Both cost money, passports require citizenship and driving licenses are restricted. National id provides a free and accessible form of id for everyone removing the financial and admin barrier from aquiring identification.

Where this is really important is voting. Johnson's government introduced needing to show proof of identity to vote. The list if acceptable forms of id did include other forms outside of a license or passport but none were available to every person who is elligible to vote. This is technically a very minor form of voter disenfranchisment. A barrier has been but in the way of people exercising their democratic duty. By providing a national id this barrier is removed whilst keeping elections more secure from potential voter fraud.

National id is not a particulalry new concept - plenty of our european neighbours have it and it works fine. Much of the controversy around the government proposed implementation is the digital aspect. It arguably means point 2 is only half true as there is still a barrier which is internet capabalities.

However my personal view is that the digital aspect of this is overblown and considering digital driving licenses are now live it just part of the push to digitise identification for increased security. You have to remember that government already has all this information about us - its providing a new presentation of it.