First of all I think you are giving HMRC a little more credit than they deserve, but fine, make of it what you will.
Regarding different passports, it's quite simple really, I look at the queue's and decide which one I'm going to use, hence the comment.
As for tax, the answer is pay some! don't try and rig the hand in your favour too much.
There are plenty of legal ways to AVOID, not EVADE tax, you just need to know the rules, and more importantly how they are applied. And before anyone asks, no I'm not talking about dummy corporations in Guernsey or any of that self employed rubbish.
Last year HMRC effectively sent me a cheque for about 800 quid, all thanks to depreciation, works and improvements and of course me following the rules, after I had spent about 100 days there, this year I will owe then about 600.