For questions such as “what’s the capital gains tax annual exemption this year?” here are some guides…
The ICAEW detailed data table Rates and allowances november 2018. And a version for 2020 here (although at the time of positing not fully updated, eg for corporation tax rates).
The CIOT exam version CTA-Tax-Tables-2019 and updated 2020 versions here.
My own mindmap version of some key taxes (and if you like diagrams instead of lists) Tax figures 2019 version and Tax figures 2020 version version
Other visual formats
I really like the visual version from Julius Bar tax rates 2020 julius bar version (although note that Entrepreneurs’ Relief is now called Business Asset Disposal Relief)