P&O are as close as you get to bargain basement cruising IMO,hard to beat the prices you see in the tv ads like £1099 for a 15 night Caribbean cruise which I have seen even lower near the sailing date,tips included,drinks at UK pub prices(depending on where you live of course),specialty dining at reasonable prices,likewise shore excursions.
I am sure many will say that it isn't as glamorous as it once was,room servicing is only once a day,food isn't what it once was,I think you just have to look at how little you are paying & not expect the golden 'good old days',be realistic & you will hopefully enjoy yourself!😎