A couple more for you:-
www.cws4x4.co.uk/range-rover-parts.htm (Somerset) - 01458 834930
www.equicar.co.uk (Wolverhampton) 01902 882 883
www.famousfour.co.uk/used_parts/used_parts.php?vehicle=rrp38a (Louth, Lincs) 01507 609444
www.tjclandrovers.co.uk/accessories.htm - (Kings Lynn, Norfolk) 01328 838484
www.4x4breakers.net (Norwich, Norfolk) - 01508 55 88 22
www.lrr.co.uk (London SE7) 0208 293 9091
www.amazon4x4.com (Newtoft, Lincs) 01673 863322
www.landroversalvage.co.uk (Shropshire) - 01938 561203 ~ 07761 544793 ~ 07967 219154
Martin Toole Range Rover Recycled Parts (Southampton) 07885 399785
Finally I would post on the forums (Difflock, Mud Club, LRM, LRO) WANTED: P38 engine etc.
Also, email the post to me and Ill insert it on all the smaller forums I belong to.
Finally, If you do find an engine, let me know as myself or someone on here may be able to collect it for you whilst on their travels.
Thats it happy hunting!