Please note that you may face penalties.
30% careless, 70% deliberate -through its possible to get reductions:
Delayed tax payments= 5% of Potential lost revenue.
Note for past errors you have two options (after netting off the errors)
(i) to correct the errors on the next VAT return of the errors less than £10k or 1% of turnover (max £50k)
(ii) if more, then you need to make a voluntary disclosure to HMRC.
Hope this helps.