Managing the project
Unless you are a building expert you will need a professional project manager to oversee the development for you. Whether it’s a builder or the architect make sure it is someone you trust and have checked that they have relevant experience and if possible ask to see some of their completed projects and ask for references. If the last project fell behind schedule or over budget rethink your options. If you are going to use an architect, ask to see their portfolio.
The best way to find someone to project manage your development is personal recommendation.
However, you may feel competent enough to project manage yourself. If you do this, it will work out cheaper. Just make sure you are aware of what’s involved – you will need good organisation and communication skills, and good contacts to call upon. Talk to someone who has managed this type of project before and get an idea of what you could come up against.