I'm afraid that I don't know enough about the subject to even have an opinion, especially about socio-political issues in Europe. (I'm a Canuck, so our situation is a lot different than yours. Our super-low population density is only one factor in that.)
All that I can offer is what I would think if you were on this side of the pond. If you are using plastic that is already in existence, rather than creating new stuff with the intention of recycling it in future operations, I consider that preferable to using vegetable-based material. At least it gets the stuff out of the landfills. If you don't use it, then maybe nobody else will either and it will just continue to accumulate. It will also be much cheaper if you already have the infrastructure in place; I assume that using biomatter would require a whole new processing system.
The only reason that I mentioned plants at all was because I know nothing about chemistry and can't figure out how you would make "traditional" plastic biodegradable. I guess that it's technically "organic" since it's made out of dead dinosaurs, but I have yet to see a Pepsi bottle disintegrate spontaneously.
