Dress - I have one exactly like this that I can lend you. Size 8, not worn yet cause I dunno where to wear it XD I think it's just above the knee... and the lace would make it match the shoes!
 
Belt - I have one kiiind of like this one that you can also borrow if you want. It's a sort of stone/cream/beige colour though so would depend on what other stuff you want to wear with it, colour-wise
 
Jewellery - again with the sparkly stuff XD goes nicely with black lace, imho :> whatever you can find in Claire's/New Look/etc. I figured if you're gonna wear a watch it should have a white, black or sparkly strap
 
Handbag - wasn't so sure about what to do for this, if I'm honest... I was looking for something with gems on it lol. The sparklier the better! Maybe not black cause then it'd kind of fade into the dress, but any colour that would go with the belt or is the same colour
 
Tights - nude sheer gloss ones would be best, I tink. There's enough black in the dress and shoes so a bit of skin colour would be good :>

Admittedly this is the more expensive one, but I'll see if I can help you out :>
 
Blazer - £25 from New Look, the light blue one. Could easily be a similar cardigan if you have one. Something colourful to offset the black, but still smart.
 
Jewellery - you could easily find something like this in Claire's or something like that, unless you have something already? Either way, a necklace and earrings would make the whole thing look 'dressier' and give it a sort of focal point...
 
Belt - again, just found something, but essentially if it's a decorative belt and goes with the colour scheme, it'll work XD
 
Bag - any evening-type handbag. This is just one I already had saved in my items =p I think black would go best if you're going to have a light/bright jacket or cardigan
 
Tights - sheer black gloss! Not entirely plain, but still not fighting for attention with the shoes

There, I made a better one!

Entirely from New Look... except that I couldn't find the shoes and belt on here so I just found some that look similar =p