Self build mortgage brokers

[patp]

We are hoping to finance the build of the shell ourselves. We then have the option of selling our house, moving into a caravan, and finishing the build with the equity we acquire from the house sale. We own the plot and it has planning permission.

 

I would prefer not to move into the caravan if at all possible. Would we get a mortgage in the above situation? We are both retired and on very modest pensions but debt free. I am thinking that they could use the existing house as security on the loan. We could speed on with the build, sell the house, and pay back the mortgage fairly promptly.