The higher the valuation the more you'll pay in insurance. Also, if you get charged import tax, you'll pay at a higher level.
We packed our own stuff. Gave a vague description on the manifest, down-valued, and didn't have insurance.
The only breakages we had were caused by wilful damage by Customs staff at Izmir during transhipment from the container onto a local vehicle.
If you've got any items of value that are breakable, consider bringing them when you fly, or give them to someone in the UK for safe keeping.