Hi Clementine, yes that product seems to fit the bill, had to laugh though coming from Derbyshire eh? Long way from the coast

Then again heard somewhere recently that you are never further then 65 miles from the coast in England no matter where you are...soooo fair enough.
The peeing thing is really just providing a massive hit of Urea, human urine can be used but in 10:1 dilution and very sparingly on established trees, I've used it anually on my orchids....young fruit trees? sure
maybe twice a year in spring and late autumn......but they shouldn't need the Urea to be honest with you.