Whilst we try and work out what relay you need (we need that photo) could you supply some more information to help us to help you.
a) Year make and model of the Mo Ho. Different MoHo manufacturers put the relays in different places.
"Peugeot" is tha maker of the chassis.
If you don't know who made the moho send us photo of the outside of the vehicle as there will almost certainly be the makers name somewhere.
The maker of the motor home will be "Bailey" or Swift" or something like that.
b) A few of us are surprised that you have concluded that a single relay controls the step and the fridge.
Please post a link to the thread on here that led you to that conclusion so we can check your logic.
c) you seem concerned about replacing a relay.
This video shows how simple it is. (your relay will almost certainly not be under the bonnet!)
The only thing missing from the video is to check the ignition isn't on before you start.