After selecting your Parcelforce service when setting up your Printing Label (see Creating and Printing a Label) you will be able to select Collection. This will incur an additional charge and the system will show your updated cost.
Collection of your Parcelforce parcel will take place between 8:30am and 5pm on weekdays. Collection is guaranteed to happen the day after booking if you have booked the service by 11pm. Collection is likely (but not guaranteed) same day if you have booked the service by 10am.
UPDATED: 10 June 2021