You may like to check the date of your note. I cannot align the year 1934 and the serial prefix "Y".
A Reserve Bank of New Zealand 1934 Ten Shilling note (Issue 1)(Governor L Lefeaux - serial Y 842585?), uncirculated and in absolute mint condition could fetch anything up to $6,500 NZD. If it has been circulated but still in good condition, it might fetch anything from $50 to $3,500 NZD.
A reputable coin dealer will be able to give a more accurate valuation.
A Reserve Bank of New Zealand Ten Shilling note (Issue 1)(Governor L. Lefeaux - serial 7Z), uncirculated and in absolute mint condition could fetch anything up to $5,000 NZD. If it has been circulated but still in good condition, it might fetch anything from $120 to $1,100 NZD. A reputable coin dealer will be able to give a more accurate valuation.
A Reserve Bank of New Zealand Ten Shilling note (Issue 1 - Serial 5Z - Governor L. Lefeaux), uncirculated and in absolute mint condition could fetch anything up to $5,500 NZD. If it has been circulated but still in good condition, it might fetch anything from $130 to $2,750 NZD. A reputable coin dealer will be able to give a more accurate valuation.
A Reserve Bank of New Zealand Ten Shilling note (Issue 1 - Serial 7Z - Governor L. Lefeaux), uncirculated and in absolute mint condition could fetch anything up to $5,500 NZD. If it has been circulated but still in good condition, it might fetch anything from $130 to $2,750 NZD. A reputable coin dealer will be able to give a more accurate valuation.
Such a banknote does not exist. Serial Y is possibly from 1938.A Reserve Bank of New Zealand Ten Shilling note (Issue 1)(Governor L Lefeaux - serial Y), uncirculated and in absolute mint condition could fetch anything up to $6,500 NZD. If it has been circulated but still in good condition, it might fetch anything from $150 to $3,500 NZD.A reputable coin dealer will be able to give a more accurate valuation.
The last New Zealand Shilling was minted in 1965.
A Reserve Bank of New Zealand One Pound note (Governor L. Lefeaux)(serial 3C 220165), uncirculated and in absolute mint condition could fetch anything up to $4,000 NZD. If it has been circulated but still in good condition, it might fetch anything from $70 to $2,000 NZD. A reputable coin dealer will be able to give a more accurate valuation.
A Reserve Bank of New Zealand One Pound note (Governor L. Lefeaux)(serial 1D 095863), uncirculated and in absolute mint condition could fetch anything up to $4,500 NZD. If it has been circulated but still in good condition, it might fetch anything from $95 to $2,400 NZD. A reputable coin dealer will be able to give a more accurate valuation.
New Zealand has never issued a 20 Shilling coin.
A Reserve Bank of New Zealand 1938? Ten Shilling note (Governor - L Lefeaux)(serial Y), uncirculated and in absolute mint condition could fetch anything up to $6,000 NZD. If it has been circulated but still in good condition, it might fetch anything from $150 to $3,500 NZD. A reputable coin dealer will be able to give a more accurate valuation.
New Zealand has never produced a 50 Shilling coin/note.
There were twelve predecimal Pennies in a Shilling, as used by many of the British Commonwealth countries. The British Shilling converted to 5 New Pence at the changeover to decimal currency. The Australian and New Zealand Shilling converted to 10 cents at the changeover to decimal currency.
A New Zealand 1965 Shilling (Proof), does not get a valuation in any catalogue. There were only 10 minted, so that puts into the category of extremely rare and therefore unattainable. A New Zealand 1965 Shilling (Proof like), uncirculated and in absolute mint condition could fetch up to $10 NZD. There were 25,000 minted. A reputable coin dealer will be able to give a more accurate valuation.