What happens if nota wins?

It's a common query, but the UK doesn't have an official NOTA option. People can 'spoil' their ballot paper as a protest, perhaps by writing 'none' on it. However, this has no legal impact on the result. Even if spoiled ballots were the largest group, they are simply discounted. The candidate with the most valid votes in the constituency still wins the seat. It's a feature of our First Past The Post system. A 'win' for spoiled ballots is purely a symbolic gesture; it doesn't trigger a new election or disqualify candidates.