Although I do have allotment, I do grow lot of crops in containers too...potatoes, beans, herbs, salads, roots, etc, etc.
As for preffered 'recipes'..well, it all comes down to what I'm aiming to grow. The principals for container growing is not that different to the growing in ground..it is just in smaller scale and you might have to take improvement different qualities to more extreme than in ground.
As what to use for improvements...grit is good for adding drainage..but again, some plant prefer something lighter and less 'lumpy' around their roots so then I would use perlite..or even vermiculate. But having a allotment allows me to have room for storing all manner of different materials.
You will go far with just few 'incredients'...multipurpose compost, top soil, grit and some basic fertilizers..and yes..you can use water retaining gel too, adjusting the amount of each thing for what you are trying to achieve.
Large terracotta pots are good to line with old compost bags to keep soil moist...I find that growing in terracotta pots soil dry out much quicker than in plastic or metal containers.
Aim to use some amount of topsoil in your mixes as compost on its own will shrink away container edges and once the surface dry out it will make a crust that will have be broken down or the water will just run off without penetrating any deeper and the roots are still left dry.
Salad crops and radishes are ideal 'after crops' as they don't need much nutrients, spent compost is ideal for them.
One incredient that I would not be without is Jonn Innes base fertilizer..I use it to 'return' the feed into spent compost..growing become very expensive hobby if compost is discarded after each year. Same compost/soil can be use time and time again when it is just refreshed with bit of 'fresh' compost and added base mix.
Other two 'regulars' in my stach is blood, fish and bone meal (BFB) and chicken pellets.
If you have access to grass clippings and straw..those come handy too..they are great as mulches or bulking up large containers when it is not necessary to fill it all with soil/compost. Lot of quick salad crops don't need deep soil and for those I may fill 1/3 of deep container first with straw or even broken down polystyrene tray pieces..saves a lot of work and compost.
Potatoes that need deep containers and lot of root room..it will take huge amount of 'bedding' to accommodate even few plants..so when I grow potatoes in buckets, I use spent compost alternating with thin layersgrass clippings every few inches and sprinkling some BFB meal and chicken pellets in between layers...building the 'soil' level up as the plants grow.
Carrots prefer more soil based mixture with added sand..unless you grow stumpy type,, those are not fussy as they don't tend to fork..again..just bit of BFB mixed in for nutrients and they should do fine.
Runnerbeans...pile up anything and everything and they will use up all the nutrients and moisture for their lush growth. I would not mix anything fresh like grass clippings but use those as mulch..half composted plant material is ideal at the bottom of the container as it will hold on to moisture.
You might be bit challenged with veg growing on north facing garden...but, untill you've tried you won't know what veg will succeed in your garden's growing conditions. Good luck with your 'venture'.
I do have lot of container growing ideas..but it would help to know more of what crops you are planning to grow to keep amount of typing down..