Minimal to zero gains going from your 82mm tubs to wheel combinations above. Tyres and good glue job matters more.
Timetrialling Forum is local to you and reasonably often has second hand track disc wheels for sale if you still want a disc rear. For cheap skins suits, the guys in that forum recommend a UK ebay seller - graceo_titanium_bolts
Good shoe covers are faster but as the UK are similar to Australia following UCI rules to the letter they aren't allowed indoors.