I have never composted before.

My council is offering up to two Blackwall Compost Converters (330
litre) per household. A two month trial then £19 each including
delivery (RRP £49.95 it is claimed).

Optional Accessories:

Composter bases at £9 each "to improve aeration and drainage" (RRP
£12.95);

Organica Activator at £5 each "500 ml bottle should last at least a
year" (RRP £7.15);

Compost aerator at £6.95 (rrp £9.95).

Please advise as a new person to composting what is necesary, what is
cheap etc? What is an unnecessary accessory?

Cheers
Colin