I can't make any difference and it depends on how many seats the LibDems pick up and how many Labout lose (I think both are inevitable). I wouldn't want the LDs to go into another formal coalition with anybody, but it's possible they will hold the balance of power, much as they do now in the Lords. They could then pick and choose which bits they wanted to oppose. No, I don't think they would spend an extra £500 billion, but they have, for example, campaigned for more resources for mental health for a long time. They would hold the government to account for any post-Brexit moves, such as scrapping workers' rights. Labour has now said it will rubber stamp the Brexit deal. I'm absolutely sure the LDs wouldn't.
Not saying I'm right, but that's what I'd like to see.