Readers' forum: Buying the plot

I am buying a one-third acre plot with planning permission for two properties. I will sell my home to make the purchase and start building. The first house will be my main residence. I want to divide the plot into two and sell the second as soon as possible to avoid needing a mortgage which I would otherwise require to finish building the first property.

I expect to rent accommodation until March when I will move into a caravan on the land. How long would I need to live there in the caravan for the other half of the garden to be classified as my primary residence when I sell it?

If I continued to live in a rented property but the double plot was my only owned...