HMG reserves the right to tax what it calls "Government Pensions" in the UK irrespective of where you reside on this Planet. The Military Pension is just one example of a "Government Pension". My Wife was in Education and her Pension is also classed as a "Government Pension" as are ex members of the Civil Service, Police etc.
The State Old Age Pension will continue to be index linked providing there is a bi-lateral treaty between HMG and your new Country of residence - eg such a treaty applies to all EEC Countries.
Suggest you talk to Paymaster (01293 604057) re Military Pension and the State Pensions people in Newcastle (details from your local Jobcentre).
PS Only one "M"in emigration.