You are NOT self employed. PARC and eJ may tell you that you are, but you are definitely not.
Let me ask you these questions (before HMRC does):
1) Are you provided with a roster?
2) Are you provided with tools? i.e. an aircraft, a crew room, charts etc
3) Do you provide your Piloting services to more than one operator?
4) If you are sick, do you have someone you send in your place to act as a "sub"?
If you can answer NO to 1 + 2 and YES to 3 + 4, then you may have a chance. But, we all know and HMRC know that this is clearly not the case. Be careful. And I'd be careful about bragging about your Tax affairs on PPRUNE. It's a bit dumb to be honest.