Weight Cheapie (Chinese crabon fun)

I'm probably going to give it to a mechanic to put together.

I'm not too bad with connecting x bone to y, though stuff like grease/lubing and (more importantly on this one) the various torque concerns are perhaps left to a pro.

Does anyone have any recommendations for guys that will (in London)? The less they'll look down on me for buying chinese and/or not from the shop the better...
Brixton Cycles.

Or buy a torque wrench.