I have made some awful puns on this site but I have never got as low as "What ever 'tips your boat' (pardon the pun!)" .....or have I? Nice one Cyril .... Neil
You can opt out of the tipping system and pay your own to who you want to. You can't opt out of 15% added to drinks prices, so it's still a rip off! Sort it out at the start and forget about it.
Might I suggest that you go to "Find a question" at the top of this page and pick from the topics section "Tips/Gratuities" and have a look at the thousands of views already expressed there. It could give you a great insight of the British mind or it may totally confuse you but it is worth a look. ..... Neil.
It's entirely YOUR choice. Nobody can tell you what to do. If you are happy to pay the £140 extra then who's stopping you? If you don't, again, who's stopping you?
If you are happy to pay then nothing more needs to be done. However, if you'd prefer to opt out it's best to do it as soon as you arrive on board. Hoping there isn't a queue at the purser's desk it takes a matter of minutes.
Some people are happy to pay it, others are not. What ever 'tips your boat' (pardon the pun!).