What are the rules for sending marmite and creams abroad?
Let's deal with this question in general. There are are a number of different potential rules that come into play:
- The export rules of the initiating country.
- The rules the carrier you are using.
- The import rules of the receiving country.
In specifics, since you are sending items within the EU which are not banned anywhere and do not have excise duty, you are golden for export/import.
If you are using The Post Office then they will apply the Universal Postal Union (UPU) rules, if you are using an independent carrier then they will apply theirs. Your question mirrors a belief that there is a universal regulation for sending items internationally -- there isn't. The UPU binds normal post but every carrier is free to carry whatever they want (more interesting items often at a price you do not want to pay, however -- transporting spent nuclear fuel will cost a bit more than transporting coal).
Whether the company in question treats creams and (barely) edible shoeshine as liquid is perhaps easiest clarified by calling them and not waiting for someone to wander in here who happened to attempt to send these specific items by that courier.