How to drive on dual carriageways:
A dual carriageway is a road with a central reservation separating traffic travelling in different directions. It is not necessarily two lanes in each direction, it could be just one lane each way. A road with 3 lanes in each direction could be a single carriageway, if there is no central reservation. An example of a single carriageway with 2 lanes in each direction is Victoria Avenue, in Southend, between Priory Park and the Blue Boar.
As soon as you enter the slip road check that there is nothing parked at the end of it, where it joins the main road. Then accelerate to match your speed with the main road traffic - holding in 3rd will maximise acceleration. Keep with the kerb* and use the whole length of the slip road to reduce the angle of approach to the main road, and hence minimise your blindspot.
Check your right side mirror frequently, and your blind spot at least 3 times (photo above), don’t twist your shoulders or you may swerve. Vehicles on the main road may try to move to their right to let you out. Be careful though, they may indicate right, but not be able to move because of other traffic overtaking them. Try to change your speed, by accelerating more, just before you cross the line as you enter the main road. This means that anyone hidden in your blindspot will drop back, and you will see them.
* Entering the main road, the left hand lane of the slip road is preferred. Because using the left-hand lane means that if you cannot emerge due to heavy traffic (in an emergency) you have room on your left to manoeuvre into; without worrying about other traffic on your left.
When leaving the main dual-carriageway you may need to be careful when you indicate because of other turnings. If you indicate too early you may cause someone emerging from an earlier turning to pull-out in front of you, because they think that you are turning into it. In this situation you still need to indicate, but do it late so that your indication is not misinterpreted.
An example of this would be when leaving the A127 (London bound) at Pound Lane - if you indicate too early it may look as though you are turning into Alton Garden Centre.