Andrew it will be fine on standard plug. This is done all the time without problems.

Clive is also correct that 1.5mm2 is fine for the connection between VFD and Spindle. 2.5mm2 should be used from mains to VFD but to the spindle you are better with 1.5mm2 because it's easier to fit into the spindle connection socket and because the spindle is only rated 8A then 1.5mm2 is more than enough.
In use while cutting you'll rarely if ever pull the full 8A.
I don't set my VFD to Display RPM just Amps so I can monitor for cutter wear so I'm very aware of the current they pull. For instance milling aluminium 4mm DOC full slot engagement with 8mm 3 flute cutter running 1000mm/min I only pull around 3A when cutter is new. Max is 5A when cutter is so worn it's crying stop.!!
Only when you jam up or Bog down will you get close or exceed 8A in which case the VFD should be set to Fault if above set amount for any period of time.