Since motorway driving is not covered on the UK driving test, you will not have any previous practical experience of this face paced environment, so here is a video clip showing how to join the motorway. Driving on a dual carriageway does not necessarilly mean you will be able to safely deal with motorway conditions.
As a driving instructor, in my professional opinion I would advice you to have a motorway driving lesson with a fully qualified ADI to boost your confidence and make sure you know how to be safe, it is better to make a mistake with an instructor than alone.
Otherwise you can take a pass plus course, where motorway driving is one of the modules, and you will learn the differences between it and a dual carriageway where you can also drive up to 70mph.
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