Well it depends on what you mean by young really. The choice of chubby girls increases considerably as you head up towards the mystical age of "29" and beyond.
Some girls I have seen who are I'd say are definitely young by any reasonable standard and would recommend highly:
Voluptuous Ebillie, a very charming black girl. At the moment she seems to be doing weekend tours in different parts of the country.
YoungBustyScarlett, top girl with huge boobs. I think currently only doing outcalls in the NW
bbw_alexis, lovely blonde girl in East London.
All these are friendly girls with a professional attitude. Don't think you could go wrong with any of them.