Would these floral topshop shorts go with these coral flats + a basic white top?

No that would be so cute! If you're unsure you can do a basic copy and paste picture in Paint or Photoshop or even Publisher. Get a picture of a white tank top, put the picture of the shorts underneath it, and then then paste the shoes under the shorts. That'll give you a better idea of what it'll look like cos I know I suck at visualizing things (women normally are apparently) :-)