BEIS publishes estimates of greenhouse gas emissions in the UK each year, with historical data on a consistent basis. The latest estimates going back to 1990 and including a provisional 2019 estimate can be found here: https://www.gov.uk/government/statistics/provisional-uk-greenhouse-gas-emissions-national-statistics-2019. They show that an estimated 435 million tonnes of carbon dioxide equivalent (MtCO2e) were emitted in 2019 in the UK, down from 794 MtCO2e in 1990.
In addition, estimates of carbon dioxide emissions in the UK since 1970 are available in table 4 in the data tables accompanying the final 2018 greenhouse gas estimates: https://www.gov.uk/government/statistics/final-uk-greenhouse-gas-emissions-national-statistics-1990-to-2018. The estimates for 1970 to 1989 do not include all of the sources of carbon dioxide emission included for 1990 onwards and estimates for other greenhouse gases are not available before 1990.