Not the Hilton by any respect, but a cheapy.
The Royal Hotel is in Purfleet is about 20 min's away. It use to be a travel lodge so the pub/resturant is in staggering distance, but they built a bigger one down the road. The last time I stayed there it was £35 per room (Feb 2004).
There number is 01708 865432.
There's also an Ibis in the Lakeside retail park, a Travellodge in the Lakeside/Thurrock services and a Travel Inn in Chafford Hundred, just up the A1306 towards Grays.
All of them are just over the bridge, 5-10mins drive from site.