Captain Stable has posted the text of the CAA document on the safety forum. The use that the photos will be put to is not relevant to deciding whether it is aerial work.
You need to check the first paragraph of article 130 of the Air Navigation Order:
"Public transport and aerial work
130 - (1)
(a) Subject to the provisions of this article, aerial work means any purpose (other than public transport) for which an aircraft is flown if valuable consideration is given or promised in respect of the flight or the purpose of the flight.
(b) If the only such valuable consideration consists of remuneration for the services of the pilot the flight shall be deemed to be a private flight for the purposes of Part III of this Order."
The remainder of the article deals with public transport.