Since you are British, you should be able to apply for British citizenship for your children straight away; they wouldn't require visas. A few routes may be available for your wife, depending on how long she intends to remain in the UK; she may be able to apply for a spouse visa, for example.
How can naturalized British citizens living abroad obtain British citizenship for their children?
I became a British citizen 10 years ago when I was working in the UK. Soon after, I had left the country and now I'm running a business where my wife, a Turkish national, is expecting. Would my children be eligible for British citizenship automatically or should I consider an UK Tier 1 Investor Visa for my wife and soon-to-be child?