My only address is in the UK, what do I do to continue? I am a deemed resident and don't have a Canadian address so the programme isn't letting me continue.

When using TurboTax Free and filing a deemed resident income tax return, you will need to input a Canadian address on the return.  When you print it, you can manually change the address to your U.K. address.  As a deemed resident, you will need to print and mail your income tax return.  Unfortunately, you will not be able to NETFILE.