Spoilt ballots ARE published but only at the constituency/ward level - an email to the Returning Officer is all that is required. usually about 0.50% unless there are large number of candidates and/or the elector can vote for two or more candidates when it can reach the dizzy heights of 1%. Not collated at the national level though as legislation very much stresses local nature and administration of elections in the UK. Even Euro elections in a region overseen by a single local authority returning officer, not a civil servant.
As someone who worked on over 30 elections since 1984 I can assure posters that we get plenty of ballots marked 'none of the above' , and far worse!
Compulsory census -once every decade, hardly a major task or infringement of our 'uman rights.
On the other side of the coin i have also observed with a cynical smile that many of the most voluble refuseniks about big brother firm filling can be the quickest to complain if 'the state' fails to give them maximum opportunity to object to any planning and development issues, for example. The link may be entirely unrelated though!