Hi Aldi don't have a code of practice its basically a gmp audit with parts of the brc thrown in. Make sure your pest control, fabrication, haccp meetings are all up to date and that your ccp's are being followed properly then you should be ok so long as your gmp is good! It will depend on your product a bit as well anything product specific eg allergens species control should be good. After that they will do a trace usually and will check the product quality. If you have had a lidl audit its very similar.
Good luck 😊