As usual with electoral politics (and as you would expect a Leninist to say), the main value is in propaganda. The very fact of having an MP in a Labour heartland, gained representation at several levels with impressive victories in local councils, and having threatened several other safe Labour seats, has given us an ability to punch above our weight in the media, and raise criticisms of the government, the war etc that are almost never raised. Galloway has been a very effective interlocutor with the media, as have Rees, German, Yaqoob et al. Concretely, we can work best on a local level, so for example we've helped stop local council housing from being privatised, provided support to striking workers, helped negotiate a peace in Birmingham when 'race riots' were threatened, challenged the implementation of the Crossrail programme, worked to build the antiwar movement, defend refugees and immigrants etc. We approach local and national politics as activists rather than bureaucrats - so, rather than simply politicking in the local town hall, we work with and within existing grass-roots networks to apply pressure, disseminate information etc.
As I see it, the main task is to break Labour's hegemony on the Left vote and in the short term reactivate radical possibilities that are steadily being foreclosed by the neoliberal parties. Since no left-of-Labour party has won a parliamentary seat with such a massive swing since 1945, and since we are taking over historic heartlands of the Labour Party in Birmingham, London and Preston in a short space of time, there is every reason to think we can do this.