Its a nice bike in near original trim.
Downsides are that Holdsworths/Clauds of that era aren't especially rare, and there is a limited market for a garden gate sized frame. The Holdsworth name does make old men get all misty eyed, but there is never a shortage of them for sale. Indeed, it was only a few years ago I was given one in that size gratis, in not much worse condition and in all original spec (I gave the vendor a beer based thank you).
On the plus side, while they're not super exotic they do ride very nicely, and that size would fit me nicely!
I think a realistic price range would be £100-£125ish, maybe a bit less because there aren't that many buyers who'll fit a 26" frame, maybe a bit more of the right buyer of the right height happens along. Im afraid you won't be going to the Bahamas on the proceeds. Those bars and stem won't help, but shouldn't be a total turn off.
If it fits you id be inclined to fit the proper (GB?) Bars and stem, and ride it. They do ride really well, and give good comfort and a surprising turn of speed for something that isn't an out and out sports machine.
BTW, the rear mech - and it likely is original - dates the bikes assembly no older than 1981. The frame may have been manufacturered in 1979, but Holdsworth are famed for keeping frames in stock and not building them up for several years, sometimes even after the model was officially deleted from the catalogue.
