tornado3raf
I have a relatively small property portfolio back in the UK which are all rented. Despite being a non resident, I am still liable to tax on income generated over the tax free allowance, (approx £10k). That includes, unfortunately, a proportion of my EK salary for when I'm undertaking UK flights. They work out a ratio of your total flying hours with a formula of layover hours and then apply this to your salary. In my case, that represented 1.6%. This percentage is then taxed at the taxable rate which applied to the income tax band. I can still have up to 90 days there, with no tax implications, providing it's not related to work.
Any form of income earned in the UK over the allowance is liable to be taxed, regardless of non resident or not. Capital gains tax does not apply when you've been a non resident for over 5 tax years and any liable asset is then disposed of whilst under the status of being non resident.
You may need to get a more up to date accountant as what you've stated is simply incorrect. Getting it wrong now could be very costly for you!