I’m not sure how it is in the U.K. but in Ireland, when I learned, you couldn’t drive on the motorway with an L-plate but the morning you passed your test you could zoom on, without ever having had a practical lesson.
My wonderful big brother taught me motorway driving skills - how to pick a car and match your speed to it on the slip lane, where all the blind spots are, how to predict other drivers intentions, what gap to leave in front and how to watch and control the space beside you so you have options, always to show brake lights when you see brake lights ahead, how and when to use hazards, to wait until the car you are overtaking is in the middle of your rear view (not side) mirror, to stay out of blind spots, what lorry drivers can and can’t see, why driving slowly can be hazardous, etc
A lot of drivers don’t understand that there is a driving lane, and two over taking lanes, or when it’s appropriate to move between them (eg making space at the slip). In Ireland, from left to right, there’s the Foostering Lane, the Driving Lane and The I’m too Special for Speed Limits Lane.
If you can take some lessons in Defensive Driving, even theoretical ones, though better if practical, it can really help with confidence because you understand what you can and can’t control.