Question about Dorking Chickens

I am wanting to start raising a small backyard flock of chickens, this is my first attempt at chickens. I am interested in the Dorking because it has a great temperment, dual purpose bird (with great meat) and I am wanting both eggs and table meat. I have read that the Dorking does not reach maturity for 2 yrs. What exactly does this mean? Will they not lay eggs for almost 2 yrs or does this mean you can wait until they are between 1 yr - 1 1/2 yrs old to process them and still have a roasting bird verses a crock pot bird. I do want to keep my breed pure, but I am also alittle worried about the broodiness of the breed. I can only house 10-13 birds. I thought that I might get a few (3) hens of another breed to supply us with eggs when the Dorkings are not laying (apparently they do not lay when they "go broody" ?). I would like the alternative breed to lay brown eggs so I can keep them seperate from the Dorking eggs. Is this something that will work in reality or only in theory? Also is there a breed you would recommend for this supplimental purpose, that will get along with the docile Dorking? Could you recommend a reputable hatchery. Thank you so much for your time.

Blessings