Dual carriageways have a central reservation separating traffic in opposite directions, which makes them safer than single carriageways at higher speeds. The national speed limit is 70 mph for cars, but you must still drive at a speed appropriate for the conditions, the traffic, and your experience.
Slip roads are where most faults occur. When joining a dual carriageway, use the acceleration lane to match the speed of traffic in the left lane. Signal early, check your mirrors and blind spot, and merge smoothly. Do not force your way in: if you need to slow down or wait, do so safely within the slip road.
Overtaking on a dual carriageway is straightforward if you follow the rules. Check your mirrors, signal, check your blind spot, and move into the right lane. Overtake decisively, then signal left and return to the left lane when you have a safe gap behind the vehicle you passed. Do not stay in the right lane longer than necessary: lane hogging is an offence.
Leave enough space. At 70 mph your stopping distance is 96 metres, about 24 car lengths. In wet conditions it is roughly double. Keep at least a two-second gap from the vehicle ahead, and increase this in rain, fog, or heavy traffic. If someone is tailgating you, ease off the accelerator slightly to increase the gap in front of you, giving yourself more room to react.
Be aware of slower vehicles (lorries, caravans, and tractors) which are limited to lower speeds. Give them space and only overtake when you have a clear view and enough room to complete the manoeuvre safely.