I've been there . That was great dining. Yes it is situated between Anuradhapura and Rambewa ,more towards Rambewa.
I think you meant Avissavella-Hatton route. I've travelled on this route many times and I've always stopped at Kitulgala Rest House managed by Ceylon Hotel Corp. Food is pretty good but a bit expensive. But you can enjoy the nice view of Kelani river while dining. When you get to Nuwera-Eliya ,there are pretty good places to dine in ,right in the middle of the town such as De Silva, Rimarco, Milano......
Again about the route- Try to take the route via Ginigathhena, Hatton to Nuwera Eliya. Constructions are completed of Hatton- Nuweraeliya road.
Going to Ginigathhena then to Nawalapitiya and to Nuweraeliya via Gampola is pointless and far. When you are coming back you can come via Ramboda, Pussellewa,Gampola to Colombo