I do not live in the UK GandTea, but it is quite normal in Europe. In Germany it is 8% of the taxes you pay. Here in Switzerland, it changes from Canton to Kanton- My Canton and Geneva have voted to make this voluntary- and it means our Churches are truly struggling to maintain workforce and services to the community, for the handicapped, elderly, alcoholics and drug users, Alzheimer sufferers, in OAP homes and hospitals, etc, etc. They sold many Vicarages and other buildings to cut expenses, and Vicar have to be shared among villages, some made redundant, some just not replaced on retirement, and staff and expenses cut to the absolute minimum- but now they just don't know what to do next.
And still those who have opted out expect to be married and buried in the Church, etc- and to just pay a small fee for the service. A neighbour even told me he told the Vicar who officiated at the dad's funeral (who had all opted out of paying the tax)- to play down the 'God' bit'- as he was not a believer. The hypocrisy beggars belief.