I don't know how much to enter?
As Stamp Duty is a legal matter this is not something that Thirdfort can advise on. We recommend contacting the organisation that referred you to Thirdfort, and they will be able to advise on how to proceed.
I'm not paying Stamp Duty
If you are not paying stamp duty as part of your purchase please enter this as £0 and you will be able to continue with the task.