Contacting HMRC

I am a long term UK expatriate in Spain and for many years have not received any tax related correspondence from HMRC. Consequently, I do not know the identity of the tax office which is responsible for my tax affairs and I cannot make any enquiries online because all your systems requires a UK postcode which is in itself a remarkable oversight. I wish to make enquiries regarding non-domicile. I would be grateful if you could provide a means of contacting the correct tax office other than by post. Thank you.

Hi,
Please contact our helpline:  
Non-UK residents: Income Tax and Capital Gains
On this page you will also see a link to Personal tax account which may be the quickest way to review information relating to pay and tax history, tax codes and how to change them.
Thank you