Where to look for boat advice and nav training
 

I am thinking of buying a boat with sail and power (something along the
lines of a converted lifeboat), with the idea of living aboard for 4 montths
of the year in the Med and Aegean.
I have had little to do with boats since I left naval school 40 years ago.
Can anyone suggest where I should look for broad advice on the type of boat
I should look for (for low-maintenance) and if and where I should seek
re-training on navigation. (My seamanship & navigation GCEs of 40 years ago
are now almost valueless!).
Many thanks, Chrisssss..... (North Wales, UK)