The Evohome app lets you override the scheduled target temperature, but only immediately. This recipe lets you set a timer to do this at a point in the future.
You can't set this trigger on IFTTT as a one-off, so I have used a trigger that repeats annually. To stop it repeating, you just need to delete the recipe (or change when it is set for) in the 364 days after it has triggered.
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