Can I run my car on E10 fuel?

I have a Peugeot 107 on a 10 plate. The specified fuel for this is E5. What is the danger if I run it on E10? Bear in mind that E10 fuel did not exist when E5 was specified for this car.

Do I need an E5 additive for my classic Daimler?

I am fortunate to have and look after a 1969 Daimler Sovereign (420). I am having to use E5 fuel and would appreciate your guidance on which additive(s) would help protect the Jaguar XK engine? I believe...