Due to not only likely opposition from both the Tory party, the entire Tory press & Labour 'centrist' MPs (along with much of the British security & military establishment) it'll be next to impossible for a future Labour government to cut funding for Trident let alone abolish it. However what a future Labour government can do is to put more stringent legal parameters on how/where/when it can be used in order to mitigate the reckless horrors Trident can unfurl.
In order to achieve this I propose that a future Labour government:
1) Prohibit current & future UK governments from the use of Trident against another state as a 'first strike option' (i.e. Trident can't be used without Britain being attacked first). Why? To use a nuclear weapon against the civilians of another state without that state having attacked Britain in my eyes (& hopefully in the eyes of many Brits) a barbarically unjustifiable act of mass murder (i.e. incinerating entire foreign cities of million+ unsuspecting inhabitants) carried out of a paranoid belief that a foreign state 'may' attack Britain in the future on the flimsiest of evidences.
2) That a current & future UK governments can only use Trident to protect the British Isles, British territories as well as maybe Canada/Australia/New Zealand. Why? Because the British public who pay for the acquisition & maintenance of Britain's Trident programme do so to use this weapon in defending Britain & British territories (as well as former British colonies whom Britain has formal & direct security ties with like Canada?), however the British has not agreed to finance Trident in order for it to be used to defend non-British linked countries like the Baltic states & Poland especially if having to use Trident on Russia in order to defend the independence of those Baltic states & Poland creates the risk of having British cities (e.g. Manchester/Birmingham/London/Newcastle) incinerated (like Hiroshima & Nagasaki?) by Russian nukes.
I believe that by having a future Labour government commit to creating these above mentioned legal parameters on the use of Trident by future UK governments in order to prevent the reckless use of Trident & the potential horrors it can bring to civilians (foreigners & Brits) will be something that can be less seriously challenged by Tories & centrists because placing legal parameters on the use of Trident amongs the majority of the public (including those in 'middle england' as there is enough of an isolationist - admirers of Peter Hitchens - that dislikes 'foreign entanglements' as much internationalist leftists) is more popular/viable proposition then committing to the outright abolition of Trident.