Nope, he means 70 mph (113 km/h), and yes, you just gotta pull out of a T junction and go; no merging lane, no on-ramp. That's a dual carriageway, characterised by two lanes and a central barrier (single carriageways are usually national speed limit, i.e. 60 mph). Bear in mind that as with everywhere else, most people are travelling 10 - 20 mph over the indicated speed limit (and thus probably travelling around 75-80 real mph). Underpowered automatics are death traps.
That said I drive a BMW 330D (straight 6 3L diesel) manual, which probably would be fine as an automatic.