TBH on a flat white I wouldn't bother spending £40 on a wax, in fact not even sure I would bother with a wax at all.
You would be better off getting a decent sealant on.
I would be tempted to get:
Shampoo - Chemical Guys Extreme Body Wash & Wax.
Light polishes/ paint cleaners - Sonus Paint Cleaner or Autoglym Super Resin - contain fillers, to reduce minor swirls, which you will probably have a few of still even though you have PCd the car. They also create a surface for the sealant to bond to.
Sealant - JEFFS Accrylic, or else Chemical Guys Jetseal, or Autoglym Extreme Gloss Protection.
Tyres - Blackfire Long Lasting Gel.
If you are still wanting to get a wax too, I can personally recommend Collinites 476s for being good on matt-coloured cars and providing excellent protection and a very good gloss. Not tried any of the Dodo waxes but people seem very pleased with them, but on a white you aren't going to get any depth to the paint, so no point buying an expensive wax as you won't notice the difference.