Hi henrys how are you?
it doesn't work like that, the parties are allowed to ask people how they voted outside the polling station and they are allowed to offer lifts to the polling stations, but when u are in the booth, you could spoil your paper accidentally on purpose or just leave it blank, noone would know that you had done that, they know if you turn up to vote as you have to present your card and postal votes are recorded, but noone would be concerned iof u had never voted, or even surious unless the political party campagn managers had done lots and lots of homework over the years.