Hope that you get your PUG on time, and Welcome
As for the 206 cc 2l i would not expect to get any where near 100 miles for £10, you might get 100 miles for around £20 to start with if the car is new?.
There are many who are have the same problems with the MPG that they are getting and the MPG that PUG say that they should be getting.
The bst thing to do is to test the MPG that you get over, for example a half tank of petrol like i have been doing and if you feel that it is low then take it back to your dealer and as them to look at it.
Good driving and let us know how you get on.