Magnum Pinot kit best before march 2023

[latchy]

Hi Folks,
I've been inactive for the last few years but have now decided to get going again.
First off is the Magnum, I'm assuming the yeast will be stale so I've bought a 5g high alcohol wine yeast to replace it.
The yeast with the kit has nutrient, my replacement doesn't. I've read that lemon juice or black tea is a good source of nutrient,
but in what quantity?

Thanks

 

[latchy]

Went ahead and made the kit this afternoon. The disconcerting thing is that when I opened the tin the contents were dark, odd I thought for a white wine.
I mixed some of the old yeast nutrient sachet in a little warm water with a teaspoon of sugar and it wasn't very active but I threw it in the brew anyway, mixed it in then sprinkled the new yeast over the top. The airlock is bubbling away merrily at 25C.
Worst case scenario I've wasted 3.5kg of sugar