Okay so to add a bit more detail to this, the company that I own is contracted by them, rather than me personally. However, the options that we have been awarded, are to both my business partner and I personally (due to some funny business where our company was not legible to accept them).
You should be taking to a proper accountant then, and not taking advice from here. Funny business usually leads to additional taxation, penalties and interest. For you, your company, and the client.
Not an answer to your question,but something you might consider in any case:
Arguably, you aren't, because of the monthly pay and option grant.
This impacts what NI and income tax you pay, how you pay tax on any option exercises, and how the startup pays NI.
(I may be making some completely incorrect assumptions, of course.)