We had 3 companies in for quotes and are usinf the company that we felt most comfortable with - Dorree Bonner. They also have a lot of recommendations on the forums. To date they have been really helpful with quuestions etc so I am confident it will go smoothly (touch wood!!)
They are based in Dartford but i think they work all over the UK.
Hope this helps.
Can't help you with prices though as we are sharing a container