For me Steve,you should keep finding ways to make Pesos at source once you are sure this is where you will spend your money long term..All these UK investments are fine IF the exchange rates stay stable..
If the exchange rates continue to go down then its best to spend your pounds in the UK where they have at least some value.
The UK Pounds that we have left will stay in the bank as it pisses me off to much to change any at the moment!