Just to clarify, the potential penalties and interest are:
Until you receive any written information from HMRC take anything told on the phone with a pinch of salt as they may be paraphrasing. What I've said above is just to give you pre-warning.
- A penalty for failure to notify (hopefully this won't be charged),
- A penalty/penalties for late payment, (30 days late = 5% of tax owed, 6 months late = another 5%, 12 months late = another 5%)
- Interest charged from the date it was due to be paid until the date you actually pay the tax.
Note - there's also penalties for filing a tax return late, however, if you haven't had a notice to file yet then there shouldn't be any penalties.
Sounds like I have received more poor communication from HMRC. Not surprising.