Fair dealing
The lawful use of copyrighted works in the UK falls under the term 'fair dealing'. The following is a list of relevant instances of 'fair dealing' as outlined by the UK Intellectual Property Office:
The majority of the image usage for research done at SIA will be covered under fair dealing, but don't forget to properly reference the pieces.
Creative Commons
If you have concerns regarding copyrighted materials, one suggestion might be to use images which use one of the Creative Commons licences. Licensing under Creative Commons allows content creators to determine how their work can be used and attributed.