However, the official records are available at The National Archives - see the TNA research guide at https://www.nationalarchives.gov.uk/help-with-your-research/research-guides/bomb-census-survey-records-1940-1945/ - though unfortunately these records haven't been digitised for download. A freely downloadable dataset listing the 32,000 bombing raids on Britain in WW2 compiled from intelligence reports in The National Archives is available at http://www.warstateandsociety.com/Bombing-Britain. According to this dataset, raids on Exeter St. Thomas which caused the most casualties occurred on the nights of 23/24 April and 24/25 April 1942 and TNA's Discovery catalogue lists reference HO 192/868 as providing details of the damage caused.
If you can obtain a copy, I understand that the HMSO publication "The Defence of the United Kingdom", by Basil Collier, HMSO, London 1957, is meant to provide a good account of the so-called 'Baedeker raids' on Britain. A contents list is available at https://www.ibiblio.org/hyperwar/UN/UK/UK-Defence-UK/index.html from which it would appear that the Baedeker raids are described in Appendix XXXVI (The Führer's Order for the 'Baedeker' Offensive) and a bomb map for the Exeter raid of 3 May 1942 appears as Map 28 (The Bombing of Exeter, Night of 3rd May, 1942).