In the EU, We have similar consumer protections for online purchases¹: a cooling off period of 14 days where no reason has to be provided for cancelling an online purchase of products or services (I’d wager the UK consumer protections are pre-Brexit rules that remain in effect). You’re actually better off making an impulse purchase online than you are in a bricks-and-mortar store.

¹ https://europa.eu/youreurope/citizens/consumers/shopping/gua...