Not to put a downer on it but why did you go for such a deep water transducer living in the UK.
I had the airmar tm 260 which is basically the same transducer. I fish offshore for both pelagic upper water colum fish as well as deep drop fishing with big ellectric reels capable of fishing 1000m +.
Most of my deep drop fishing was in water 300-550m deep, at these depths I saw no improvement over the lowrance transducer $1100 cheaper. The cheaper transducer could easely show fish on the bottom as well as show my 5kg sinkers when using the units menu to select only the bottom 50m of water.
The 260 more often than not flipped out in deep water often telling me I was in 2m off water, it rarely stayed connected with the bottom. Just to add the correct transducer was sellected in the head units menu and the second transducer was disscinected.
For shallow water work in 60-80m once again I saw no improvement and the narrow beam also missed structure and fish that the wider beam would show.
I worked closely with Lowrance tech team over several months not wanting to give up on this transducer but eventualy sold it on eBay for next to nothing
Not wanting to put you off as you may have far more luck tham me, also the warm clear water I work in will have a huge influence on why I get such good results from a $200 transducer