After cardiac ablation, how long will I have to miss work?

Not Long. People go home the same day or the day after, barring complications. We usually advise people to avoid heavy "squat" lifting for 2-3 days while the catheter entry sites heal over, but people are up and moving almost as soon as we get the "sheaths" (tubes that we put the wires through) pulled out.
Not much if AOK. If the ablation is routine and uneventful (and you are otherwise healthy), and planned often on a friday, patients have not missed work except for the day of the procedure. Occasionally, they may stay overnight and thus miss a second day. Avoiding any heavy lifting or other isometric exercise for a few days is prudent, depending on the line of work one is in. Talk to your electrophysiologist.