As OO, staying at home 6:miles off base, I would put my rain coat on over a comfy sweater and No2 trousers, drive in, do the necessary, and drive home.
What an appalling admission of idleness! I was always taught that you should imagine how you would pass scrutiny if the defaulter was inspecting you! So, well-pressed No 1 HD, polished OP shoes and your best SD cap were de rigueur - and you arrived at the Guardroom at exactly the appointed hour to the second!