If you already have an account set up with with amazon.co.uk, then you can just sign in on any of their European sites, as per normal, and you'll automatically be logged in.
The format of all of their sites is identical for ease of use. If language is a problem, use Google Chrome.
Shipping charges to the UK work out at EUR 4 per order. It's flat rate irrespective of how many items you order.
Packaging varies according to how many items are shipped. Germany tends to be the best overall. France, Italy and Spain are more variable.
Customer Service for all sites is good and each site offers an option to e-mail them in English, in the event of problems.
I've used all of their European sites and you get the opportunity for some real bargains not available on the UK site, as well as being able to expand your horizons beyond what is released domestically.