I deleted your post in the Buying a New Camera forum as it was a copy of your post here and had not attracted any replies. As your question is specific to Canon you will get the best answers in the Canon forum and I thought it best to avoid duplication. I hope you don't mind.
The 400D is an excellent choice. I had mine for a year before upgrading to the 40D. The 40D has a great deal going for it but, as you have noted, by opting for the 400D you give yourself more options, budget wise, in your choice of lens.
As you have realised, the 18-55 kit lens is fine but there are better, albeit more expensive, options out there. Have you read Gordon's article Canon EOS 400D / Digital Rebel XTi kit lens upgrade group test
? There's some excellent advice there. That said, I bought an EF 24-105mm f/4L IS USM lens with my 400D last year and haven't regretted it. If budget permits have a look at Gordon's review
(or his 40D
review which was done with the 24-105). Another possibility, though I haven't seen any tests yet, is the new EF-S 18-55mm f/3.5-5.6 IS
kit lens with Image Stabilisation as the headline feature.
If you can, I would suggest considering buying the 400D with the kit lens even if you don't use it. The reason is simply that the price difference isn't all that big and if you decide to upgrade the camera body in a year or two you might find it easier to sell the 400D if you can offer it with a lens.
I can't offer you advice on specific traders but please consider the Partner
stores and help support the site. If you go elsewhere then you can always check ResellerRatings.com
. In any event, in the UK the distance selling regulations mean you are pretty well protected, especially if you pay by credit card.
By the way, don't forget that Canon have a cashback offer on until the end of the year. £50 on the 400D (or 40D) body, £40 for the EF-S 17-55mm f/2.8 IS USM, £70 for the EF 17-40mm f/4L USM, £20 for the EF-S 17-85mm f/4-5.6 IS USM and £35 for the EF 24-105mm f/4L IS USM.
Good luck with your choices. Let us know how you get on.