There are about 60 000 British people living in Portugal, so finding like-minded people who have made the move shouldn't be a problem. This guide to retiring in Portugal might answer some of your questions.
The cost of living in Portugal compares quite favourably with the UK. For more information, read our Cost of Living in Portugal guide.
Whereabouts in Portugal are you planning to settle? The Algarves is popular with retirees, but can be more expensive than other places. Why not read some experiences of other expats in Portugal to give you some ideas?