I know the arguments. Plenty of Christians do take the creation story literally. It's not a hole. I'd even argue that it shines a light on the holes in Christian theology!
Dawkins hedges his bets. It does not 'take faith to be 100% confident that there's nothing there', as you say. This is a straw man, because Dawkins doesn't claim 100% confidence nor does he say there's nothing there.
Your 'it also takes faith' narrative rings a bit hollow, as well. Look at discussions and debates about the meaning of faith and how it's used vs a high level of confidence built on data and learning (ie, science) since...well... since the beginning of the time as we know it.
Having faith in something we cannot see or test or examine might be enough for you, and your beliefs were born.
Having a high level of confidence also creates beliefs. Yet, having a high level of confidence is not the same as having faith. If a definitive claim is made, (which Dawkins is careful to avoid because he can't be 'certain' there is no god. It can't be tested- as yet and he understands how claims work) he who makes the claim bears the burden of proving it.
As for assumptions... you say most Christians believe that the creation story is 'merely an example/story for people who had no understanding of science...' and you assume that Dawkins didn't bother to find out what Christians do believe. Pretty sure you don't know much about Dawkins and his professional life story to be able to make that assumption.
I live in the US, and let me tell you- some people do believe that those examples, those stories in the bible (which bible, btw? there are many and multiple versions) are literally true. We have Ken Hamm's Ark Experience, for crying out loud (evolution, you say? That's a myth, clearly the exhibits with humans riding dinosaurs is the truth of the matter...)
So, what do Christians believe? Well, in the absense of a clear set of defined terms in the bible, we are all left to our own group's interpretations of what we should believe. So, Dawkins goes to the leaders and to the text on which the entire religion was built.
One religion with a crap-ton of denominations and sects and break-off cults... and there are how many known religions currently? Estimates that I've seen say anywhere from 4000 to 10000, (with 4200 coming up several times when I was trying to find the answer to that question). So, there are at least that many interpretations of some books that people claim are super special (and they aren't even all using the same books or versions of the same book!).
So, couple the fact that plenty of people are taught and DO believe the truth of the stories in the bible with the fact that cherry-picking stories to suit your narrative is a game played by every. single. Christian. and you will see that this weak argument about assumptions is just a distraction.
There is a set of beliefs listed in that book... so, he goes to that book which you all claim is the basis for your belief. How much do you believe? How much does your neighbor believe? What stories are just allegory and what 'actually happened'? Did a god suspend the physical laws of nature to make a snake talk? To impregnate a virgin? Do all Christians believe in heaven and hell?
Or, is your upset at his 'assumption' just a reaction and your critique just a smokescreen so that you don't have to look closely at the arbitrary nature of religious belief and your acquiescence to authority?
I'm not trying to be rude. It doesn't matter what 'most people in the UK' believe (if you can even make that claim. I'd love to know where you got that figure, I love reading about this stuff). But making a slippery argument so that it can't be dissected and examined because you (and some others like you) don't believe in THAT part of your special book is dishonest, IMO. Because why is your belief better or more correct than the person who does believe in the literal interpretation of that book? Who is 'right'? According to your book- that literal believer is correct, isn't that right?