Boat Regs ex UK or New Zealand

[Zee Kiwi]

we are about to embark on a new adventure and would love some help on a few things and as seems always to be the case, we are getting some differing advice so have come to the experts !.


I, as the boat owner have a New Zealand and UK passport, my partner has NZ passport, currently acquiring an Irish one !
We pick up our new catamaran in la Rochelle in April and intend to sail for up to 6 months in the med.

1/Should we register the boat in UK or NZ?
2/IF NZ does this mean we have to go out of EU countries each year?
3/IF UK, do we have to pay VAT on the boat when we pick it up?
4/Is the NZ flag OK if UK registered?
BUT
from reading forums It seems that rego in one country and passports in another just creates problems?
Would love advice on this please,
ciao