Not sure that's the case, you aren't buying anything, you're investing in return for a reward. HMRC is irrelevant. It's not FCA regulated, the Consumer Credit Act 2015 doesn't apply.
Just yesterday I was reading about a cycling innovation by a Dublin-based company funded through Kickstarter. It smashed its target, but 3 years later they've just said "sorry, we've failed, we've run out of time and money, we have no product and we can't offer refunds". This was on a c€500 product. You have no recourse in that instance.
You haven't bought anything. You've made a pledge to support them and will (hopefully) be rewarded with a product of value commensurate to your investment.