Some smart TVs (like my Sony) can directly record to a USB hard drive and pause live TV. The manual will explain if it has this feature. Otherwise get an external recording device with its own Freeview receiver and storage built in. That way also you can record one channel while watching another. See Poly Hive's recent thread on DVD recording for suggestions on Freeview recorders as well as DVD writers.
The modern aternative is streaming via catchup services that your smart TV wll have some of (like BBC iPlayer), but you may get better picture quality (less compression) from your own recordings, as well as being able to keep them for longer/ever. Another option is recording with a PC fitted with a Freeview PCIe card (with single, dual or even quad tuners - recording off the air not the internet, so need an aerial input).