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I think you will find all your british appliances will be fine, we sailed her in 2006 and she had just become the Sea Princess having been the Adonia for P&O. we didn't need any electical adaptors at all.
If I remember correctly the voltage is 110v. Take an adaptor if you want to multi use the wall sockets as there are a combination of UK 3pin and US 2 pin. Variable voltage appliances would be best to take with yo.