Your statutory rights will not be affected when you buy a policy.
These include the right to claim a refund, repair, or replacement for up to six years (in Scotland it's up to five years after you became aware, or could with reasonable diligence have become aware there was a problem) if your electrical goods were not of satisfactory quality or fit for purpose when they were sold to you.
After the first six months, you will have to prove that the goods had a fault when sold to you.
For further information about your statutory rights contact the Citizens Advice Bureau: www.citizensadvice.org.uk or 03444 111 444.