As the CFI of a large club i'm, unfortunately occasionally involved in unraveling why controlled airspace has been infringed by a member or others. In virtually all cases the infringements would have been avoided should the pilot have been receiving a FIS
Surely you are kidding, Homeguard.
The way to avoid a CAS bust is to navigate accurately, not by talking to London Info who have no idea where you are.
There is an attitude in the PPL training circuit that you must talk to everybody enroute. I am not saying this is wrong but I am saying it is largely pointless.
Abroad, VFR, one talks to the regional FIS frequencies (unless instructed otherwise) and that is normal and expected, but they usually do have radar so the interaction is different.