Dare I say it, P&O UK compares well with Princess Cruises. Just more formal and more British cuisine, kippers, pork pies, Brit beers. Real English bacon not that nuked, cremated streaky American stuff.
On board currency is the GBP, but drink prices are reasonable all the same, but been about 5 years since last P&O UK cruises. I believe like Princess here, on board gratuities are 'rolled into fare.