Potato yield and manure help please

Hi guys I know it's a bit of a how long's a piece of string question, but any idea what sort of yield i can expect from 40 rocket early seed spuds and 40 maincrop stemster?

Just trying to guage what to grow on the plot to try and feed us for a period of time without taking too much room up!

I've set aside 13ft x 6ft for the earlies and 17ft x 13ft for the main crop, leaving 72ft x 12ft for everything else on a 4 year rotation.

Also am I too late to add manure to my spud plot, it is dug over and raked ready now but I forgot about adding it over winter! 

Many thanks again,

Stratts

Thanks mate the manure I can get has been sitting for years at the bottom of a heap about 30ft high, lol!!

I just about manage it -274.

I just about manage it and plant 60 

We do eat a lot of rice as well though 

Depends how big your family is and how many spuds you eat I guess

I don't worry about yield of new potatoes because I try and get them on the plate when the prices are high in the shops. Which means they are eaten when small. For that reason I have started 5  Rocket in pots in a greenhouse.
I plant 10 rows of 18 -2nd early and maincrop and we have started to buy them. (Two of us plus occasional family meals.) I have never weighed them so I cannot say what 40 tubers would make.
You have bought your seed but next year try different varieties to determine the best for you. Taste is a factor as well.
I have started to dig my trenches and I am adding manure/ compost as I do so.