SYD - SIN is dinner and light meal iirc. Wines in F are generally as advertised (it is Club that suffers from the randomiser effect). 90% of BA crew are competent to excellent but the other 10% do let the side down. There is less chance of encountering the 10% in F as the cabin is toothy like hard work the lazy.
Plane will be a 772 with the normal sized screens for the IFE.
You'll have an experience that will be somewhere between perfectly decent and truly enjoyable so relax and don't stress.