Istanbul, Worthing is on the seafront. Worthing isn't too far from Hove, (20 mins by car )but as your Dad is in Hove you might as well go to the Istanbul Barbeque on the Western Road near Waitrose. It looks as if its just a kebab shop from front but at the back is a small cafe area, the food is superb, authentic and very reasonable. Most of the customers are Turkish, so good for eavesdropping and seeing how many words you recognise. You can take your own alcohol too!
Silk Road in Littlehampton is excellent, very cheap mid week special, 2 courses and a bottle of wine £25 for 2 people. Not so authentic, as Tukish/Mediterranean, and more of a Brit clientele.