This is a hardware fault the machine machines door sensor isnt detecting the door is closed properly.
With the washing machine off, close the door and hold it firmly in place then then the washing machine on, and try and start a program (while pushing the door inwards, so its firmly closed).
The washing machine may start and give you a few extra washes while you book a repair, however it will stop working all together or it may have already failed completely.
If you provide your post code I can recommend a suitable firm to come out and do the repair.
The door sensor can be affected by a faulty actuator and works by detecting the location of the latch, by pushing the door in this can often allow the washer to detect the door being closed (it works on the majority of Hover washers with a similar fault), unfortunately it doesnt seem to have worked in your case.
With regard to arranging a repair Hover have approved repair engineers covering Oxted area, their service centre details can be found here.
The fact the washer is likely to be out of warranty, you may find it cheaper using a freelance engineer, and can recommend Mandells they have repaired a few washers in the area for me and my colleagues, their contact details are here (they open around 8.30)
Good morning sorry for the delay in responding, do you still require assistance?