There is definitely something up with Princess website in UK. I tried going on to it via my phone which I haven’t used before for looking at cruises. I get the same as you but looking carefully the price on the front page is in Euros, not pounds. I think that’s why you can’t get anywhere with finding cruises as your IP address, like mine, will be a UK one. I wonder if when booking from Europe you have to use a travel agent rather than booking direct.
However, if I use my iPad which is what I have always used for Princess I have no problem researching cruises at all. I’m assuming the cookies on that ensure I reach the right site.
I don’t know what to suggest to get on the right site I’m afraid but did want you to know that it’s not just you.