Looks like a good buy on the face of it.
The pics look good and show some good quality gear in very good condition. Bigger pics of the frame/bike would be good.
The tyres are glued, tubs, and I am sure someone here would give you a detailed lessen in changing them, I am due back at work in 5 mins so dont have enough time to go into it at the moment. The hub with two gears, one each side, is a flip flop type hub. A different gear on each side so when riding fixed and you want a slightly easier or harder gear you can just take the wheel out and spin it round the other way. No matter how many times I retype that description I just cannot seem to articulate the picture in my head, so i hope you understand or someone else helps.
So that wheel is for riding with one gear at a time. The other wheel with all the cogs will work with your rear changer and shifters on the downtube, while the gears look very similar you will feel quite a difference from the highest to the lowest.
The equiptment is of very good quality, record hubs, GP4 rims etc so I would assume that the frame is of a similar quality. Without knowing the frame and looking only at your photos I would say it £80 well spent.
Start with fixed so its simpler and get out and ride it. I am sure you will love it.
This is quite rambling and disjointed and now I am late
Hope it helps in some way.
Carlsberg dont build Singlespeeds but if they did.......they would probably look just like mine.
I've spent half my life on bikes.........the other half I wasted