i needed to tax my car today at the post office. I had to do it online because i have misplaced my insurance certificate it says it takes 5 days to come will it be ok if i drive my car and print the recipt of from my emails if not what will happen
Technically you are not allowed on the road without displaying a current tax disc. However, if stopped I very much doubt if any action will be taken if you have paid and can produce a receipt saying so.
As dilligaf says, it is rare nowadays for proceedings to be taken for failing to display. The evidence is taken from records that show your car to be covered.