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To be on the safe side, assume the instructions are for non fan ovens. That way, the worst that will happen is you’ll cook stuff on a slightly lower temperature and so it might need a bit longer.
I’d also recommend you buy an oven thermometer – you can get them cheap on eBay. It will give you a sense of how accurate your oven is. Ours is quite an expensive Bosch fan oven and it’s still up to 10c lower than the display indicates.