Not really. And once you're you've been admitted in the UK you can work in many areas so long you understand the limitations and how it's done. I know <ahem> at least one lawyer who is admitted in NZ and Oz, but lives in the US. All their actual practice work is simply funnelled back to NZ through a NZ office. Doesn't stop them acting in the US or other countries. Just means they can't practice in those countries, ie not acting for US clients in the US as a US entity or presenting themselves as a lawyer under US law.

Personally, I think you're looking at it the wrong way. The law degree is not to practice law and then travel, but rather, the law degree is to get the jobs that require or ask for a law degree and involve travel. Subtle distinction.

Off the top of my head I can think of several dozen people I know with law degrees (from quite a number of countries) in the following areas that travel for work

Government - Immigration, Foreign Affairs, Security/spy, Trade, Environment
UN - Almost everything!
WTO, IMF, & WB
Dozens of NGO's, especially the larger ones or the ones with close UN tie ups.

As I say, there are a very large number of options out there. Worst thing possible would be to think of law in the traditional way and getting the degree to go out and "practice law". Much better to think of the degree as a ticket for entry into certain occupation areas that simply prefer a law degree as the entry ticket.