A well run shop in the right area will do very well. There is no need to open excessive hours. Many chip shops are quite happy to close by about 10 and not go for the pub closing trade. They don't need it. Having said that it's a long day - deliveries from 7.30, prepping all morning, open at 11 shut for the evening about 10. Some stay open throughout, others close between 2 and 5. It's too much work for one person but the business can afford the help needed.
The National Association of Fish Fryers runs training courses, including some aimed at absolute beginners.
If an existing business is taken over, then there will be a system to follow. The products that you sell will be greatly influenced by your buying decisions - the source of fish, what type of oil, the make of pies, variety of potatoes. Changing the formula for a successful shop might alienate existing customers so anything new might need to be brought in gradually and tested.
There's the eternal problem of deciding whether to buy on price or quality. There's a place for both models - a top notch chippy can attract customers from a wide area. There's another market that isn't at all discerning and just wants to be fed cheaply.
Getting the pricing right is vital - one mistake made by newbies is not to understand that potato prices vary considerably over the year. Work out your prices when spuds are cheap and you are going to get it wrong. Fortunately there are plenty of opportunities to visit competitors and check pricing.