There are several ways to get furniture marks out of a carpet.
The easiest solution is to give the carpet a good vacuum. If that doesn't work, try giving your carpet a blow dry – spray the spot with water, then use a hairdryer to dry the carpet, fluffing it up with your fingers as you go. Keep the hairdryer at least 4 inches away from the carpet to prevent heat damage.
For stubborn indentations, a carpet cleaning machine may be the best solution. You can [hire a Rug Doctor](https://www.homebase.co.uk/brands/rug\\-doctor.list) machine from Homebase.