The excellent answer by Buffy definitely also holds from the UK perspective. I would encourage you to discuss this with your advisor, specifically so they can help advise you better (at the very least, adjust the workload and expect results accordingly).
Additionally, you say you have not yet started a PhD programme, and will start in September. While the contract allows you to take up additional 20 hours of part-time jobs, you might want to discuss possible effects on your PhD. If your PhD is indeed a part of a regular 3- or 4-year UK PhD programme, it will likely be difficult to finish without dedicating to it full-time. As funding often can't be extended, taking up additional work may result in a lower quality PhD (finished in time) or a longer PhD (with a part of it potentially unfunded). Not trying to dissuade you, just saying there might be more factors to consider.
However, I also want to say that good advisors should discuss career options with you and offer you support in your choices. And while there might be some advisors applying undue pressure on their students to stay in academia, I have not actually met many (any?) of these. Most of my colleagues are fully aware that only a small percentage of all PhD students will end up getting a permanent academic job (or even taking up a research position within academia as their next job). A vast majority of PhD students end up working in industry; the PhD just opens the doors to a larger pool of positions in industry (one would hope, better paid).
I don't think aspiring to an industry position after your PhD should be a barrier to speaking to your advisor: they should be able to explain your (industry) options following a PhD better (maybe offer an opportunity for a collaboration with industry you have not previously considered?), and if they are not supportive of your plans for professional development and growth, it may be better to find out sooner rather than later.