There is no information of any value here outside the context of the site itself - unless you're claiming that your audience is a representative sample of the UK population?
People who do this consistently over time, tend to accumulate more money, and thus accrue more influence as time goes on. Also people who bet foolishly, e.g. just bet on who they like to see winning, create opportunities for other people to make money of their back.
Do you have any evidence for this? E.g. comparisons of polling vs betting predictions from previous elections.
That describes investment as well.
In `pure' gambling, like betting on a coin flip, everyone already has all information. So it's less interesting, and warrants a different category of game.