most diesel you buy these days inthe UK has 5% biodiesel in it known as B5 and has the same spec as regualr diesel EN590 and diesels will be ok. The most common for of biodiesel is rapeseed methyl ester, cause we can grow it and its properties are pretty good in comparison to other options .In other parts of the world you willfind more palm.Soya is also used.
B100 is available but from a limited number of places.If you buy it froma pump it should be ok to use.
You can jsut pour in a few litres of value new cooking oil into your tank and it will run fine.But you are suppose to delcare it and pay the duty on it
In petrol its good old ethanol at 5%. This has been adopted very rapdly across the UK thanks to subsidy on the duty. But now in much of Europe the ethanol rather than being blended direct into petrol is being converted into ETBE
You can get 85% ethanol blend (E85) but to use it you need to make sure all the bits of rubber in the fuel system are compatible