I don't think too many of us have our pulse on the UK market. I would suggest calling all the spa companies and getting quotes. These are people that know how to move a spa properly.
Secondly, I would call moving companies and get quotes. They aren't as familiar with spas overall but may be willing to move one for a price.
Lastly, get some friends, rent a small trailer and buy beer and pizza. This one is usually the most economical...
P.S I was BORN in Sussex but I've lived in Canada since I was 7. Just a little FYI...
Steve