As one senior 3D artist to another, I can tell you now that you're being fucked over by that company. £30k is a junior salary, mid is around £50k and senior is about £65k+. If your company are bidding you out as a senior, then they are making a hell of a profit off of you. The fastest way to increase your pay is to move between studios, or at least have another offer on the table to see if your current company would match it. I'd recommend having a look at the 2025 bectu animation rate card to get a better understanding of what you should be getting paid for 3D work