As i understood it, you have 12 months to pay (not sure if you can pay x amount per month, something worth checking), as long as the finance is paid off before the 12 months is up then it's interest free.
My friend paid this way. You can pay the full balance within 12 months without paying any interest. You will have to pay a settlement fee of about £20 if you do this but that's a very reasonable price for credit.
Just make sure you do pay it all off within 12 months or you'll face some hefty interest charges.
No you do not make monthly repayments in the first 12 months.
Instead, you have the option to repay the full balance at any time before 12 months. You have to pay a £29 settlement fee when you do this. If you have not paid the remaining balance within 12 months, you will have to make monthly repayments with a very high interest rate over 4 years.