The zeroater jugs are widely available now, Ocado, Amazon, direct from importer, Morrisons and is an easier option to an RO system or buying the RO water and would suit your small tank. I get about 100 littres from each filter cartidge, but that will vary depending on your water.
There are a cuple of options I know of for Blue bolt shrimps, https://www.shrimpcorner.co.uk/freshwater-shrimp/blue-bolt-shrimps.html or https://www.pro-shrimp.co.uk/taiwan-bee-shrimp/172-taiwan-bee-wine-red-red-ruby-red-king-kong-panda.html or even ebay. Deliveries are a bit hit and miss since covid19 and obviously xmas will make that worse so bear that in mind, if you can be patient it may be better to wait until the new year????
Always drip acclimate new shrimps over a few (or more) hours before adding them to the tank!
This is the GH+ I use to get the right water (from RO) for the shrimp and it is pobably the easiest one as it is drops rather than powder, https://www.pro-shrimp.co.uk/shrimp-king/803-shrimp-king-mineral-fluid-double-gh-4001615061413.html , it will last a long time with your small tank, well over a year I would expect.
There are a lot of different foods as you will see on pro-shrimp, the main thing is NEVER overfeed (very common error) and with a small tank I would get a powder food (will be good for babies as well) or something as small as possible. Some of the foods come as quite large/hard pellets (shrimpking) which I used to use but smashed them up with a hammer, but it would be easier just to get smaller food.
Indian Almond leaves are good for shrimp but can be large for such a small tank. You can use this instead if you don't want to use the leaves as they are too big, https://www.pro-shrimp.co.uk/shrimp-king/804-shrimp-king-humin-fluid-vital-4001615061420.html .
Simon