Thanks for the replies and the links.
The aircraft was given a fresh annual before sale but I also contracted a very trusted and experienced PA28 engineer to survey it for me prior to purchase. His summing up was 'if you don't buy it, I will' and I am assured it's all up to date and in great condition for its age.
Looking forward I just need to know I am looking in the right places to be ready to note anything required. My maintenance organisation can offer CAMO cover but frankly given the low utilisation working outside a controlled environment seems to be cheaper and I get the chance to move to another company with less hassle if I do an annual each year.