Um so. I wrote some things that might come out harsh if read with the wrong kind of tone so please try to employ a happy, teasing, concerned kind of tone over the whole thing...
Price for the game is WAY too low! I'd suggest going for at least 20 pounds if not more, some people will only buy on sale. A kickstarter is for making sure a game gets made, not doing discounted pre-sales.
The benefits given are too much for such small increments. The lowest tier should be 4 pounds and it should only be a thank you and a wallpaper. The next highest should be at least 8 for a thank you and three wallpapers. Double again for all 8.
Also increase that Enough is as Good as a Feast tier. If you're giving all of those perks it needs to be more. The all 8 wall paper tier is 8, the game is 10 and the game plus all 8 wallpapers is 12?
Take another look at your prices, you deserve to be paid for you time. If you got hired to flip burgers would you be making more or less than the amount of time you spend working on these things? If it's less, espeically if it's half as much, you should be taking a hard look at why. I buy things from Etsy a lot and some people are clearly not selling at a profit; if you aren't making enough to cover your costs and some you might not be able to make another game. What if there's an unexpected issue? What if you need to hire someone else?
Just consider carefully! It's really hard for most people to put a value on their time, be kind to yourself, consider if someone was hiring you to write something as long as this VN how much would you ask for?
Only 1000 pounds for 8 CG's? Seems low. - Also only 1000 pounds for custom music? Have you done a bunch of research on the cost for that?
Add notes about the number of revisions or a set deadline for designing a character/scene/outfit. Some people will nitpick things into eternity and beyond.
And on to little nit picking...
Charlottes profile:
Not entirely sure what the last paragraph of her profile is supposed to mean. I can't decide if it meants that she is less worried about herself than she is for her brother, changing her personality to try to change her brother, or something else entirely.
Frederiques profile:
Enroll at university
Guillaumes profile:
You used nor, I'm pretty sure it's only supposed to be used if neither is used before it. I think it should just be a plain old or.
Mathys profile:
Is it supposed to be "does he hope a war will spark need of his skills once more..." or should it be "does he hope a war will spark the need of his skills once more..." ? or..?
Typo: rewards
All those backers... recognition int he credits.