I would also recommend keeping the layers and growers seperate, and going for meat strains for the table. Our experience is that even so-called dual purpose breeds such as Light Sussex are not great table birds. We had Hubbards last year; killed at 12 weeks at oven ready weight of between 51/2 and 7lbs. Light Sussex cockerels killed at 23 weeks, oven ready 41/2 lbs.
Given the age of the meat birds, they were only ever on chick crumbs and grower / finisher pellets, which are more expensive than layer pellets. Your layers won't discriminate!