From a non-educated, oops ill-educated, failed comprehensive oik!
Welcome kindred spirit!
The old network does not exist to the same extent. In fact it used to be that virtually all Etonians and Wykemists went to King's College Cambridge and New College Oxford respectively. Nowadays very few apply to these as they feel that they will not get in because off old-school ties being frowned apon.
As for reading, it depends on the subject. If DC wants to study Physics then he/she should be reading articles from eminent scientists, going to lectures at the RI or RS. But that aside general reading of well known works of fiction and poetry may add an advantage. Work experience or voluntary work always looks impressive as does DofE or CCF. Of course none of this is compulsory but would give DC the best chance in a competitive field.