Just to add a couple of other points:

Others may disagree, but I find the leg rest in WT+ very useful for getting into a decent sleeping position. As well as being wider and having a greater seat pitch, the seat also has a greater recline.

There won't be separate check-in desks for WT+ at LHR, but you may find seperate check-in desks at other airports.

You will have a choice of two options for the meal service. As you'll be served first, you won't have any problems with BA running out of your preferred choice. If anyone has special dietary requirements, you should notify BA in advance.

Hope you enjoy your trips on BA - I find WT+ a real step up from Y and I wish more carriers had premium economy.