I will be living in Portugal for most of the time coming back to the office in the UK once every 4 to 6 weeks and will maintain an address here, I would really prefer if I can continue to pay UK tax as the tax in Portugal is significantly higher and would make it difficult to remain.
From what you mention I think you'll struggle to use your UK tax residence - which seems to be what you want.
With Brexit coming up I am seeking to obtain residency or citizenship which has made this a little more complex.
This is where things get confusing. Usually to get residency you need to show a commitment to your new location. I'm not familiar with Portugal's laws, but I suspect they'll want to see you spending a good portion of your year in the country. That may be required once again for citizenship (though marriage may help).