Update:
Panic over. When I went to the office today to collect the HMRC letter infact it was just a standard Royal Mail delivery card. Similar to when money is owed due to incorrect stamps there is a box saying money owed due to import tax. I simply need to go to my local post office pay the tax, £14, (parcel value was actually £30, £6 tax + £8 post office fee) and walk out with my parcel. I somehow had a vision of having to complete a form in triplicate then weeks later go to some port to collect the parcel.
Panic over. When I went to the office today to collect the HMRC letter infact it was just a standard Royal Mail delivery card. Similar to when money is owed due to incorrect stamps there is a box saying money owed due to import tax. I simply need to go to my local post office pay the tax, £14, (parcel value was actually £30, £6 tax + £8 post office fee) and walk out with my parcel. I somehow had a vision of having to complete a form in triplicate then weeks later go to some port to collect the parcel.