I'm sympathetic, having often turned to the UK Polling Report (UKPR) for some insight into the current 'mood'.
By definition, a poll of polls is a collection of snapshots of the prevailing mood and always be on a single issue, such as a particular election or referendum. After the event, there is no reason to collect polling data and, so, UKPR will not have the information from which it feeds.
The methodology should be available from the site of the polling company, and The British Polling Council (BPC) ( http://www.britishpollingcouncil.org/ ) provides a list of its members and, importantly, as its current President, Prof John Curtice, stated just before the 2015 UK General Election:
BPC members will be making full details of their published polls
available as quickly as possible throughout the election campaign so
that everyone can come to their own view as to whether they believe
the results are robust and reliable or not. But inevitably members can
only do so for those polls for which they are themselves responsible.
If someone claims their poll was conducted by a BPC member, do please
check the claim out. It may not be true.
The data for public polling should also be available though I find this to be hit and miss, probably because it belongs to the company.