I suggest taking a train to Visakhapatnam and using the city as your base, to move around. Lambasingi is roughly 100km, by road, from Vizag. You can hire a tourist cab or a minivan depending on the size of your group. I have visited Lambasingi a number of times. The last time I visited Lambasingi was a few years ago. The road is narrow, but accessible. Repair work was in progress at a number of places, when we last visited. Being a hilly terrain that sees quite a bit of wet weather, driving on the road can sometimes be tricky, because of pot holes and small landslides.
There was some talk of AP Tourism Department building a resort at Lambasingi – not certain whether the project materialized. There were no restaurants at the place either, so do carry food and water. If you are lucky you might cross makeshift roadside tea stalls – selling sweetened tea, cheap biscuits and some fruits.
I recommend Vizag because the city has a lot to offer to tourists. There are a number of places of interest that tourists can explore - fishing hamlets with a lot of history attached, make a good day trip – one such place is Bheemlipatnam. It is a quaint little fishing hamlet with a lot of Dutch history. There are quite a few Buddhist sites located in close proximity to the city, like Thotlakonda and Bojjannakonda. Apart from these, there are natural wonders that can be explored – Red sand hills, Borra caves and the numerous waterfalls along the way. Simachalam is a temple for the devout. Kailash Giri, Submarine museum and beautiful beaches are other attractions.
Aarku valley is yet another tourist destination with wonderful weather and sites. There are a number of resorts, some privately owned and others run by the AP Tourism Department, where you can stay. Tyda Jungle Bells Resort offers cottages (they once offered tents as well). The resort organizes treks through a tribal village in the morning and bonfire and tribal dance after sunset. You can use Tyda or another resort in Aarku as a base to travel to Lambasingi. You can halt at Aarku for a couple of days and make day trips to Borra caves where the natural formations of stalactites and stalagmites will leave you spellbound.
Underestimate me...that'll be fun!