If the email doesn't get bounced, then it's gotten somewhere - if it does, it hasn't. Even if you knew for sure that an email existed - then the most you could do is send an email - and you can do that anyway!!
In instances like this, you could ask for a "read receipt", or try one of the "email has been downloaded" services.
Alternatively find a listed email for info on the "official" site, and ask for their cooperation in identifying who to send to. Then you could legitimately say you have been given their name as the correct department to answer your questionnaire. If you phrase it all correctly, you could almost make your questionnaire seem officially approved.
Or, how about approaching the UK gov, and asking for contacts to send your survey to? - once again, careful wording could be a big help.