Help and advice: Tax returns not filed and no records?

You've not filled them in for a few years - laziness or avoidance, now you're looking for a way out. You WILL have to do it, and if you can't won't the HMRC will estimate you've made the same as comparable businesses in your area. Bankruptcy won't make tax debts go away, you're in a lot of trouble of your own making. Can't say I have any sympathy for you.