http://cgi.ebay.com/ebaymotors/Metra...spagenameZWDVW
70-1771 is the metra number for harness. It should fit all the Heritage body styles.
http://cgi.ebay.com/95-05-F150-Explo...QQcmdZViewItem
METRA PART # 99-5804 for the dash kit.
This all assumes you are putting a single din unit in the truck. This is everything you need to put a standard single din Alpine, Pioneer, etc. straight into a Heritage body.
Of course there are closer vendors but these two will ship to the UK.
Just search with those part numbers in google and you should get some hits closer.