Minimising CGT on 2 properties.

My wife and I currently own our own home since 1987 and also a flat we purchased in 2005 which hs been let on AST since that date.

If we were to sell our own home now and move into the flat for a year or so would we be lible for CGT when we sold the flat. If we are liable for CGT what steps could we take to minimise the exposure.

Any advice would be greatly appreciated.