Liquid nicotine isn't sold here at all (no flavours can have any in it, no plain nic for vaping available).
We buy all our nic from China, USA or New Zealand. To my knowledge no one I know has had any problems buying 500ml of 100mg nic and getting it mailed here. Never been a problem buying a bunch of up to 24mg nic flavoured ejuice from various european/USA or Chinese sellers either.
So unless you are bringing 2 years worth of supply with you, I can't see any problems (besides the usual liquids and battery restrictions placed on passengers on passenger aircraft)
Hardware, batteries, 0mg nic flavoured juices etc are all sold openly, so zero problems buying vaping gear from vape shops or other retailers, or buying from overseas shops and getting them to mail it to you. No customs issues at all with gear.