Been there done that
Bought an EOS 350D in Florida a few years ago.
Yes the charger for the battery is different but this is easily rectified with an adapter plug that they were only too willing to supply in the shop when I purchased the camera. The Canon battery charger is dual voltage so don't worry about the 110/240v, it will charge on both.
Silly Rebel name means no one knows what model you have got when they look at it
No UK warranty can be a bit of a pain but then you need to weigh up the potential cost of paying for repairs within the first twelve months against the reduction in purchase price. Obviously if the camera was damaged and you had it insured then this would be covered seperately on the insurance (proof of purchase would probably be required) but a warranty fault ie shutter problem you would have to pay out for to get repaired, if the warranty wasn't valid in the UK.
Anything over about £50 you should declare when you enter the UK so that you can give the government 15% of its value. This helps pay for the public services we all know and love, such as helping with MP's expenses to furnish their second homes.
It's very naughty if you don't declare an imported item and I'd imagine the customs men, if there are any on duty and if they can be bothered when you arrive back in the UK, would identify smugglers by looking for items such as empty boxes which I imagine the unscrupulous amongst us would bin in the foreign country or post separately to their home address, if they really wanted to keep them to maximise resale value when they upgraded the new camera at a later date.
Bringing a camera back as hand luggage in a camera case with photographs taken of the holiday must make it doubly difficult for customs officers to do their job effectively.

It is against the law not to pay the VAT

and you should pay it on your return to the UK but even with this duty you still might get a bargain
I had the EOS 350D for about 2yrs and it worked perfectly with no problems. If I was going abroad again and was in the mood to buy a new camera I wouldn't hesitate.