Thai's usually invest in gold and/or land as it can always be sold for more money (or such is the expectation) and of course in children, it is they that will take care of most Thai's in their old age. Most Thai pensioner's are unlikely to pop over to Spain every other week nor ake up a new, and expensive, hobby. The cost of living is low, so one of these options usually covers them. Obviously, Hi-So/wealthy Thais are different - they have offshore bank accounts instead
I don't suggest you do the same for your Mrs, I'm just saying that there is little call for private pensions here and you are better getting one in the UK - it will be cheaper and safer - check it covers overseas residents though.