There were no copper 50 Pence coins minted, they are all made from a copper/nickel alloy giving them a silvery appearance. If your coin is copper coloured, it is either very seriously tarnished or somebody has plated it. Modified coins have no collector value.
British One Pound coins have never been made from copper.
The value of the copper in a 2 Pence coin would be significantly less then 10% of the face value of the coin at the time the coin was minted. Today, it might be a little more, about 0.2 Pence.
There were no copper 20 Pence coins minted, they are all made from a copper/nickel alloy giving them a silvery appearance. If your coin is copper coloured, it is either very seriously tarnished or somebody has plated it. Modified coins have no collector value.
British copper Pennies were last minted in 1860. If you have a Penny that old in good condition, you might be better off taking it to a reputable coin dealer for a valuation. Alternatively, the scrap value might be a few pence.
There were no British 1979 20 Pence coins minted.
There was no 1974 British 25 Pence coin minted.
It would have the same value as what it says on. If its 1 cent/pence it would be valued at 1 cent/pence.
The first British 50 New Pence coin was issued in 1969.
The British 20 Pence coin was first released in 1982.
The first British 20 Pence coin was issued in 1982.
Such a coin does not exist. The British 50 Pence coin was first issued in 1969.
There was no 1978 British 25 Pence coin minted.
The "face value" of a coin is whatever is inscribed on it, hence the term "face value". The face value of a 10 Pence coin is 10 Pence.