This is a bit of a minefield! We all know about the problems with single use plastic, straws, cutlery, food containers etc.
The UK government had vowed to ban single use plastics by 2020! We are still waiting for that bit of legislation however many restaurants and food outlets are already supplying compostable PLA and CPLA cutlery which is great, but how do you dispose of it?
PLA and CPLA is only compostable in a high temperature industrial compost facility known as an In Vessel Composter (IVC). Your garden and food waste when collected by the council will go to an IVC to be turned into compost and resold.
While in theory your PLA and CPLA could be compostable this way, the infrastructue is not yet there in order to deal with it. A lot of man power would be needed to go through the waste to ensure that the plastic that has been put in is PLA or CPlA and not ordinary plastic.
Similarly PLA and CPLA cannot be recycled the same as PET, HDPE or other plastics. So unfortunately your compostable cutlery still should go in the general waste.
If however your plastic bag or cutlery specifically says Home Compostable then by all means put it in your home compost.