Working in the UK as self-employed but non-resident

[jackf89]

I'm not a UK resident and live in other EU country where I am self employed. However, this tax year I visited my girlfriend in the UK regularly and spent several months in the UK (around 2 months in total so not enough to be resident). I just need my computer to work so I can work from anywhere and my clients are world-wide and don't care where I am.

Even though I'm not resident in the UK, I assume I have to declare the earnings I made while I was working from the UK.

1) Is this correct? I know double taxation treaties will apply so I can declare the tax I paid in my home country

2) Do I have to register as self-employed in the UK?

I'd actually like to register so I can pay class 2 NI and get more years (I used to live in the UK in the past for a few years). But can I register as self-employed when I'm not a UK resident?

[maths]

Depending upon where you are resident it is highly likely that between that country and the UK (if there is a DTA) that any UK source profits will not be subject to UK tax unless you operate in the from a fixed base which seems unlikely.

Even in the absence of a DTA a UK tax exposure seems unlikely.