Put a duff or £empty PAYG Sim into any Windows or Android phone, then put the phone in WiFi HotSpot mode, it wont give you Internet but it will default as a Wireless Router. Just rename the Hot Spot and Password the same as your home router 
You can of course put a valid Voice or Data Sim i there if you trust everyone with your Data Allowance. 
Didn't think of that one  
Shows how long its been since I had anything but a iPhone  
Would it work with a blackberry or old Iphone connected via a USB to said laptop Mr golllum (with 3 L's)   
 
Dont play with iPhones or Blackberries, but guessing if you can put them in HotSpot mode then they should work as a Router. 
Dont understand where the USB lead comes into play via the Lappy?, think you might be confusing a RG45 Network Cable with a USB Lead?, the phone in HotSpot mode becomes a WiFi Router (Wireless Hub) so just connect your Lappy via WiFi then connect your other devices through the Router as you would at Home, most modern Phones will throughput at 54 mbs for up to 5 devices so plenty of bandwidth to play with before it complains.   .
. 
USB is more to power the phone tbh.
I've run a cat5 network around the house for the various fixed t'nternet capable devices so i've got a pretty good idea about RG45 ect  
 
 
The site we use is mostly statics with just 2 strips of pikey vans on there.
One end is for people who have paid for a hard standing and basically live there for 9 months of the year.
The other is normally booked up by clubs so you normally get a little bit of noise but to be fair, 90% are all regulars so everybody is pretty friendly and considerate to the point of that if there is going to be a bit of noise, the vans close normally get a invite anyway  
 
 
In all, not a bad site at all  
 
 
As a added bonus, its only 2.5 miles away from were we store the van so a brown paper bag over head to hide the embarrassment when towing it is not normally needed   
 
  
 