Hi
Usually by the time your piggies come home their body temperature should have stabilised again and they should have eaten a bit of food on their own volition. Normal room temperatures around 20 C are fine.
You can use half-heated microwaveable pads (snugglesafes) for your piggy ideally underneath their favourity cosy or a fleece mat you place their favourite hut on and change more frequently but you need to always allow space for your ill piggies to move away from a source of heat as soon as they feel overheated. By not heating the snugglesafes fully, indoors piggies are more inclined to use them in my own experience. This gives your piggies more control over their own comfort levels.
At the best, your piggy should be only a bit subdued and sore but behaving like normal.
Tips For Post-operative Care
All the best.