yep thats it
push the wheel forward and unloop the chain from the bottom of the chainring
i stand next to the bike and with one hand hold the rear of the bike up and the next roll the wheel out enough that you can wobble the chain from the sprocket and put the rear on the ground
worth noting the sturmey archer is quite a weighty hub so dont hold the wheel with your finger tips
make sure everything on the gear cable is tight before unscrewing it although its arbitary when the wheel has to sit an extra half inch further back to get correct tension when before the chain was hanging in the breeze
so be ready to readjust the 3speed . which isnt hard
as for tension . pull the wheel so its relatively straight and the chain about tight and tighten the left wheel nut so its snug enough not to move . with your left hand on the chainstay push the rim with your thumb which in turn moves the right hand side of the axle back in the dropout . with your right hand ( you havnt moved your left ) check the tension on the chain . it should be tight enough not to flap but not so tight it binds . tighten the right hand side nut . you will most likely be left with a wheel that tracks slightly to the right ( ie the tyre has more clearance on the left than the right ) just loosen the left nut and center the tyre in the stays and tighten fully . check the right nut is tight . thats called "walking" the wheel . it doesnt take into account concentricity of the chanring or sprocket but i have yet to find a sturmey archer equiped bike that requires that level of fine tension adjustment
"It also has a seat. I don’t use it, but you probably will for the first few years until you build up the muscle."