Can I travel from the UK to Portugal with an expiry date on?
You can if you have Portuguese Carto do Cidado valid. Or a valid UK resident card. But I believe you can renew your PT passport in the Portuguese consular services in UK. It will be a safer choice. Because if you do not have a valid ID somehow, they will not you board any plane. And coming by car/train/bus they might ask you for ID somewhere in the trip and you would be in trouble. Renew in UK.