A coin struck on one side only will have some value as a collectible "mis-struck" coin, but I doubt a blank unstruck planchet will have any value above curiosity value.
There may be people interested in collecting them, but if there are, they are keeping it a secret.
Most coin catalogues do not even give them a mention, other than to explain what they are.
130 British Pence is equal to One Pound and 30 Pence.
There are 100 British Pence in One British Pound. If you refer to predecimal British currency, 100 old pence would equal 8 Shillings and 4 Pence.
There are 50 British Pence in a British 50p coin.
Five pence - British coin - was created in 1968.
Ten pence - British coin - was created in 1968.
The British 20 Pence and 50 Pence coins are both heptagons.
Twenty pence - British coin - was created in 1982.
Fifty pence - British coin - was created in 1969.
340 decimal British Pounds converts to 34,000 decimal British Pence. 340 predecimal British Pounds converts to 81,600 predecimal British Pence.
There were no British 1979 20 Pence coins minted.
There was no 1974 British 25 Pence coin minted.
254 Pence = Two Pounds and 54 Pence.