As of 2021 your leccy bill was
29.28%
wholesale costs (buying leccy from the generators)
23.37% network costs (local and national grid operator costs)
16.34% operating costs (costs for your supplier like metering staff an backend bill stuff
inc pre tax margin)
25.48% environmental and social obligations
4.76% VAT
2.09% other direct costs
Source
In 2016 it was
38%
wholesale costs (buying leccy from the generators)
26% network costs (local and national grid operator costs)
17% operating costs (costs for your supplier like metering staff an backend bill stuff
not inc pre tax margin)
8% environmental and social obligations
5% VAT
5% Supplier pre-tax margin
1% other direct costs
Source
edit: I'm stuggling to find the breakdown of wholesale costs I have been told that it is about 80% fuel costs and about 10% operating costs like wages and maintenance.