Welcome to the forum Melanie, nice to have you join us. Getting a balance between easy handling and adapted to your climate might involve looking into keeping an F1 cow herd and using a third breed to provide the final slaughter generation.
For your area, British breeds especially "Celtic" cattle will cope the best, Hereford are one of the best tempered of these, but there are herds within all breeds that are better tempered than the normal for the breed.
The Galloway is exelent for winter conditions, but can be highly stung if not selected from a herd selected for better temperament, the other drawback is that they retain too much hair even in summer which is a problem at the abattoir, as the hair needs to be clipped to prevent contamination of the carcase, by crossing with a smooth haired breed, the F1 will shed the hair in summer to a more acceptable length. The Sussex is a good breed for this purpose, or go really extreme and cross to the Bonsmara! (see the photos of Bonsmara buls in Canada on the link!), the F1 will shed well in summer, and provide a high level of heterosis.
See what you think, and we can discuss your options further.