C2/C3/C4 etc - these are all types of drone that don’t yet exist, you can’t buy them, no need to worry about them yet.
You have a legacy drone weighing <2kg. See this post:
If you get an A2 CofC qualification, you can fly it anywhere you like but no closer than 50m horizontally to uninvolved people (this is known as subcategory A2). Until the end of 2022.
Without that qualification (and in any case after 2022) you can fly it 150m away from residential, industrial, commercial and recreational areas, and also at least 50m from uninvolved people (this is known as subcategory A3).
You can do better than that if you have a PfCO or get its replacement, an Operational Authorisation. You can also do better if you are a member of one of the model flying associations such as BMFA.