You do what you can with the time that you have. All of the Leaders within our Group know that if something comes up then cover is there to make sure the evenings continue. I am self employed and can never guarantee that I can be back in time for the evenings entertainment, others are the same. It does depend on the Group arrangements of course as some are better than others, ours works well because we make it that way.
As for the rest of the requirements - CRB will need to be done again for the Association but of course that's only a formality. I was the same having been a teacher myself so always seems that the processes repeat themselves. Then of course there is the obligatory Safeguarding training and a range of training modules to undertake, but that can be done over quite a period of time and not that difficult. Then what you do beyond that is up to you really. We have set up a DofE group to run with the Explorer Section and are undertaking the HML Qualification but that is because we have chosen to do so.
At the end of the day you do what your personal circumstances allow you to do.