'Declined' simply refers to a situation where you've asked an insurer to provide you with cover and they've said "No way, mate!". However it doesn't matter to you anyway, as I'll explain below:
Your motoring conviction is spent. If you're asked if you've ever been banned from driving you can lawfully answer 'No'.
Further, because the Rehabilitation of Offenders Act covers 'circumstances ancillary to a spent conviction', as well as the conviction itself, if you've ever been declined insurance solely because of your drink-driving conviction, you can lawfully answer 'No' to a question asking if you've ever had motoring insurance declined. (The same would apply if you were asked if you've ever had motoring insurance cancelled. Even if you had, as long as it was solely because of your drink-driving conviction, you can lawfully answer 'No').
http://hub.unlock.org.uk/knowledgebase/motoring-convictions-and-the-rehabilitation-of-offenders-act/
However a drink-driving on your licence can't be removed for 11 years from the date of conviction, so that's the one thing you'll have to live with for a bit longer:
https://www.gov.uk/penalty-points-endorsements/how-long-endorsements-stay-on-your-driving-licence