dont know of any fitters, dont live round their, if fitted, it will come with electrics, you will only need single for your trailer, twin electrics are for folding campers/caravans, and some posher Trailer Tents,
The cost depends upon your car, I had one fitted to my punto for £80 inc VAT, but My Multipla has cost £160 and im sure some 4x4s cost more
We had Jamie Gill from Ipswich to do ours, (we're just outside Chelmsford). He comes to the house and was excellent. 01473 658018 Mob 07795 810185. Give him a ring and get a quote, the price depends on vehicle, single/twin electrics etc.
Hubby generally does ours but suggests you ask Homestead Caravans, Weeley, or Indespension at Ipswich. If not apparently any competent auto-electrician should be able to help you.
Got a quote from Indespension in Ipswich, £170 fitted. Sounds reasonable, thats for a basic bar with single electrics. Does that compare well with you guys experiences.