had a KA - it had a handy little lip a the bottom of the filler access flap to hang your filler cap on. For my UP I have put a little hook on with sticky fixer so that keys and filler cap do not hang against the body. Only thing where Ford beat VW on design.
No need for any little hooks. If you remove the lockable cap and examine the end opposite to where the key goes, you will see that there are four gaps in the flange. This enables you to slot the cap onto the filler flap in such a way that the keyhole is facing upwards. Your keys, if left in the lock, will hang down over the flap - but as it's plastic, then no harm done.