I don't think you'll find any ready-made PCBs/shields with 240V relays, but Mouser/Newark/Digikey would all have large numbers of options.
In order to recommend a relay, we'd need to know what DC voltages you have available (are you powering your project with 5V, 9V, 12V?) and what side of the planet you're on (set your location in your profile). Here's a good example for one that would be easily wired up though:
Thank you for the reply. My location is now set. I am using a 24V DC from another set of relays . DC42 , I have used a similar board to the one you reference for another project and I am also worried about how much they can withstand a highly demanding application.