I'd start by checking the connectors under the seats haven't worked loose, and you can visually check the wiring is still intact and hasn't snapped or frayed.
The warning light will stay on now until it is reset. A garage will be able to do that for you, but will almost certainly charge you more than it would cost to buy a code reader and do it yourself. There are many available on places like Amazon and eBay, they aren't expensive. Alternatively you could ask around friends/family as you may find someone already has one. If you post your location here, there may be a local member who'd do it for you. However you'll need to address the root cause or it'll just come back on again.
If you do buy a code reader, you'll need an adapter like this one:
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The port is in the engine bay, under a round plastic cap about the size of a coaster next to the nearside suspension strut tower