Residency problem due to company contract change

[Brexitconfusion]

Hello everyone,
I currently work for a tour operator and was originally employed in the UK after moving over to the UK from Greece to be with my partner who is a British citizen. My employment began in April 2016 and I am a posted seasonal worker on a fixed term contract that works overseas and changes destination on a regular basis. This summer I’ll be working in Greece. The company I am working for, as mentioned before, originally issued contracts from the UK. This has since changed and as of 1st March 2018 my contract is now to be issued from Switzerland. This will mean that my social security will be paid into Switzerland rather than into the UK. This will therefore mean that I have no ties with England apart from the obvious (registered doctors, registered dentist, address – my partners parents’, bank account, national insurance number, tax residency etc). I do not pay any bills here in the UK or rent my own property as stated above, I simply live here through the winter whilst not working overseas for my company (this could be a period of between three and six months). This has been fine up until our contract change and the upcoming worry of Brexit. I have also never claimed benefits here in the UK as I have had work and would not wish to do so even if I had not, due to my own personal morals.Due to the issues raised above I now have come to a cross in the roads where I now worry for my future in the UK. Eventually I wish to apply for British citizenship and feel that due to my company’s contracts moving abroad I will not have the basis to apply for this. I also have been with my partner now for three and a half years and do not want Brexit or my circumstances to affect our relationship as he is a British Citizen. On top of the above mentioned I have also contacted the Greek Embassy in England who has advised me that no one knows what will happen after Brexit and that they presume everything will be fine. I have contacted HMRC Immigration who again could not help due to what happens after Brexit being unknown. This is now my last port of call for information regarding my situation and I hope that it is something you can help with or at least advise me on.The company has used TUPE to change the contracts and everything is completely above board and legal. I do however wonder on what my human rights are, as a member of the European Union when it comes to companies maybe restricting my rights to live in a country I wish to and with the partner I wish to be with? I also wonder on my rights to remain in the UK following Brexit considering the issues that have been raised above? The only other option I can possibly think of to support my rights to live in the UK would be to marry my partner. Although in the future it is something that we have talked about, it is not something to be taken lightly and definitely not something to jump into just because we have no other choice. I feel as though I am being pushed from one person to the next with no actual help or advice being given that is of any use to myself and my life. On top of this I feel I will be pushed to make harsh decisions between my relationship, life and work. 
What would you advise me to do before Brexit so I don’t have to worry about my right to live in the UK? Is certificate of residence or permanent residency something that I could do for my situation?
Thank you in advance for your help.

[secret.simon]

Provided you are self-sufficient (on your salary from Switzerland, in a Swiss bank account no doubt ) and are absent from the UK for less than six months in a year, you should be able to retain your residence in the UK if you have Comprehensive Sickness Insurance (essentially private health insurance) until the time you acquire Permanent Residence (assuming that you maintain your residence here, April 2021).

There is not expected to be any changes to the legal status post-Brexit of EEA citizens who are already currently resident in the UK.

It would be a good idea to apply for a Registration Certificate. Always keep a paper trail.

[Brexitconfusion]

Thank you very much for your quick reply.
At the moment I will be getting paid in an English bank account cause I’m not living in Switzerland.
It’s my company that moved the contracts there.
Do you know the requirements to able to be self sufficient?
I think you need to earn a specific amount a year to be able to class as self sufficient in the uk and it’s something that I’m not eligible at the moment.
I was looking for something more easier as I live here but I don’t know my choices. I don’t want to go on benefits or use any of the uk services. I just wanted to make sure my residency will not be affected due to my company’s changes.