But when you arrive in the UK they will ask you “why are you coming here?” and if you answer “I live here, my life is here, my job is here, my family are here” and present a US passport with no UK visa or other documents showing permission to reside in Britain they’re going to start asking a lot more questions.

You keep talking about “safely” running these programs. What is the threat that you are trying to protect yourself against? Are you concerned that your unofficial copy of the program may contain malware, are you worried that the copyright owners may try to find you (via IP address perhaps?) and prosecute, or what.