I am going to be residing back in the UK as a British citizen.I plan?
Your UK passport is valid to enter the UK (or indeed any EU member state) up to and including its expiry date. However, dependent on how close your travel date is to expiry, and your assessment of the risk of any delays, you may wish to renew it first. It also depends on which countries you intend to transit through. If you are entering any of those countries - lets say for example youre in South America somewhere and youre flying home via the USA - then you would have a problem, as you cannot transit the USA airside and must always clear immigration.