The Liberal Democrats and SNP bother have moderate social-democratic policies without being particularly left-wing generally.

Jeremy Corbyn (current leader of the labour party) released a very interesting 'digital democracy manifesto' during his leadership campaign, though it isn't officially labour party policy (and probably will never be). There's a more in depth paper somewhere, but this is a short summary: https://d3n8a8pro7vhmx.cloudfront.net/corbynstays/pages/329/...