Norway Nails sells lots of cool nail polishes! They ship to all over Europe, and outside Europe on request.
Use the code RAINBOWIFYME10 to get 10% off your order
Born Pretty Store sells polishes and stuff for nail art, and they have free shipping no matter where you're situated.
Use the code JCJ61 to get 10% off your order
Moyou London sells lots of really cool stamping plates. They ship from the UK.
15off might give you 15% off if you're lucky. If you buy for more than £15 you get free shipping.