Moving to England from US w/dual citizenship

Most of the information I'm finding on moving to England concerns non-citizens.  I was born in England to an American mother so I have dual citizenship.  I have been considering moving back.  I have quite a bit of family there.  What exactly do I need to do in terms of moving there legally?  I have copies of my british birth certificate and I'm almost positive my parents have the original stored somewhere.  I'm not sure exactly what paperwork is needed to get a job there.  Would I just need to apply for a passport or is there anything else?

Also, I'm a recent college grad so i don't have a lot of work experience, mostly just general office work.  Is there anything I could find before moving, or would it be best to just wing it? 

And finally, I am engaged, but not married.  What would the process be for bringing my fiance?  Would it be better to wait until we are married or would she be able to get a visa/whatever she needed easily even without us actually being married?

Thank you in advance.

Hey bro,

I also have dual citizenship with New Zealand and Ireland (which effectively is the same as british for UK purposes). The deal is you just need to apply for and get your british passport and you can just stroll on in to the country as your effectively a citizen. Just make sure you have funds to support yourself.

As for your fiancee i'm not so sure. I know that if you are married she is entitled to a british passport but im not aware of any non commonwealth visa schemes she may be able to apply for.

Just give the british high commission in USA an email and they should tell you exactly what the deal is. hope this helps