Try Silver Vision`s website. They are the company that provide wwf videos in the uk.Although having just looked at thier website I can tell you most of thier titles r region 2, THEY DO HAVE WWF INVASION. (£19.99 inc vat) on DVD.
ALSO why not try:
www.hmv.co.uk
www.Amazon.com
HMV should have a good selection of Titles
and Amazon should let you order dvds of any region code or pre-order them for thier Uk release dates.
You can always do a web search via yahoo or another search engine for what U R after, if these are of little/no help.