newish to grow your own

Hi, mostly grown stuff in pots for the last few years but this year we have just had 2 raised beds consructed, they are full of soil but I wanted to add some manure, struggled to get any so while in the garden centre today getting my first ever seed pots (pentland javelin, rocket and charlotte) saw some organic chicken manure pellets on BOGOF, will these be ok to use and should I do it now, before I plant potatoes? (I did buy them)
Also, another question, opinions on rocket potatoes, so far have only read negative reviews of them, no flavour etc, did'nt know what to buy today so went for above 3 as they sounded good, had Charlotte before so know we like them.

I've just put horse manure where my spuds are going. Do you put slug pellets under the spuds before you plant them or scatter them around after.