The choice of where to live while you build is an important one to factor into the cost of your project unless you are lucky enough to be able to avail of free accommodation (living with family or friends has a cost, albeit not financial).

A popular option is to build the garage first to live in, which will provide shelter under lock and key to store tools and other materials. However, this may trigger the need to notify the planners you plan to live in the garage temporarily which would require applications for change of use. Also be mindful that, especially with young children, building sites are dangerous places even when there is no one on site doing work. 

The alternative is to live in a caravan but it is not for the fainthearted, especially in winter.

With direct labour, which can take two years to complete, rented accommodation could work against you in terms of cash flow. That said, investing in a caravan will require an upfront investment, and selling it on once you can move into the house.