You need to report it to dvla at 0800 when the phone line opens and they will give you a ref number you need to keep so if pulled by vosa or plod you’re covered. Driving without one at all could be classes as driving without keeping a record maybe? Not worth the hassle or fine when you can get a ref. Make sure you send off for it asap to, you should carry your digi card even when on analogue to as the dvla database knows you have one and vosa may ask you to produce it as I think we are required to carry it by law coffeeholic will be better qualified then me with the fine details.