Hi and welcome to the forum.
As others suggested it might be well worth it to go and post on the See a reader topic, as plenty of the members will be willing to show off their shiny readers to anyone they can corner ( Myself included
).
Another option may be to pop down to a Sony Style store. A few members have mentioned that they were able to play around with demo models there, and do may be worth a try.
And as for the PDF's, I think, the Sony does come preloaded with a few PDF's but perhaps someone who has gotten one of the new UK models can confirm.
Finally, I can also suggest concidering getting the Cybook Gen3. WH Smith has a great deal online, for £180 making it cheaper then then the Sony and you get a bucketload of more features such as html, dictionary support, etc. and the ability to buy from a lot of online stores at prices much cheaper then Waterstones or even WH Smith.
It is however back ordered with them right now so you may be in for a bit of a wait. PDF support is decent on it, but probably not as good as the sony as it does not suppot reflow.