Graphics card shouldn't give a problem with with the digital switch.
What does sometimes cause a problem are, ironically, some of the older digital TV cards. By default they can't handle the way in which the multiplexes are reallocated to the various channels once the analogue service is switched off, and often need to be manually pointed at the correct frequencies to scan. Some of the older Avermedia cards are good examples of this
If you look up the local transmitter on
UK digital switchover dates | ukfree.tv - independent free digital TV advice you can find the correct frequencies for your area