Do NOT plug in the Anova in the UK with just a plug adapter. If you do, the Anova will be toast, because you'll be sending 230 V mains voltage into a unit designed for 110 V. That's instant death.
Because of the fairly high power consumption of the Anova, using a step-down transformer isn't a cost-effective option. It'll be cheaper to buy a new Anova for use in Europe than to buy a step-down transformer.
Michi.