My first thought is that a 12kw supply seems rather high,and therefore expensive. Are you sure you need all that? Our supply was 3kw when we first got the house (in the Gers) and we upped it to 6kw to see how that would be; and rather surprisingly its been fine; no trip-outs. We have a 13 amp electric oven, washing machine, small hot water immersion, hi-fi, occasional electric panel heaters (to supplement the woodburner), an arc-welder,and various power tools. We just don't use the washing machine when the oven is on, which isn't hard to remember. An electric kettle seems unecessarily extravagant if there's a gas hob to boil a kettle on. 6kw is quite a bit cheaper so worth trying. Good luck