Dear Mr Silly
As others have pointed out, the airports do not allocate slots - it is done by ACL.
So here's some light reading for you. This the Slot Allocation Statutory Instrument where you can see the EU regulation taken into British Law.
https://www.acl-uk.org/wp-content/up...Regulation.pdf
If you are still interested, the EU legislation is here
EUR-Lex - l24085 - EN - EUR-Lex
And just in case you don't know who ACL are (who do the slot allocation in the UK), here's their website
https://www.acl-uk.org/about-us/