Can I lease my buy-to-let properties to a limited company I own at rents which cover my mortgage interest payments, in order for that company let them out to tenants at full market rents and thereby pay corporation tax on the profits at 20%, rather than income tax at 40%? I will not be taking any salary or dividend from the company.

Certainly you can. You just need to be aware that if you let a property at a non-commercial rent there are restrictions on loss claims – see: www.hmrc.gov.uk/manuals/pimmanual/PIM2220.htm. And it is only tax efficient to do so if you (a higher rate taxpayer) do not take a salary or dividends - as you have written. You can possibly pay dividends to a shareholder who is a basic rate taxpayer, or wait for a year in which you yourself are a basic rate taxpayer and then pay yourself a dividend. Or become non UK resident and pay yourself a dividend.