I have some suggestions related to the comments above and will get to them over a few days (I'm as busy as a one legged man in a bum kicking contest launching 3 books in December). There's so much above with which I struggled to agree. On the layout side, take yourselves to Draft2Digital (https://draft2digital.com/), register, fill in the book details, load up any cover file you have, and your MS, then wait while it formats your novel. You will then be shown a standard layout which you can read as if on a phone. If you're happy with that, then select which genre your book is and D2D will give prettied up samples of the whole book. Mine is paranormal/fantasy and rather than pay heaps, I settled on their design. Then I exported an ePub file, PDF, and mobi file to my computer and the ePub I loaded up to Amazon. That cost no money but remember not to push the publish button. Just keep changing things until you find the best available. The style change in front of your eyes as soon as you push the button. I settled on the sample attached, but there's many to choose from. They won't light up graphic designers, but for the average reader you'll find a style that's okay. AND IT"S FREE! They do the contents page, which makes that easy, and the upload to Amazon was no more than a button push and it was accepted.
With the covers, the prices for which above I found staggering, there are many options. Many schools have graphic design courses. Speak to the person in charge, offer some money = maybe 50 pounds, and run a competition with the students. You'll find a good design and the winner will provide you with finished art as they learn on programs like, Gimp and others which are designed for the job. Go to Fiverr, look around at the work offered, its's cheap and you may find a good person there. I do my own basic designs on Powerpoint and send them off to be improved and finished, = much cheaper. More later.