it's great to see this thread has had 35 post's
and being honest it's about a bike that an awful lot of people wouldn't give shed room to
so a big thanks goes to all the cc er's who have contributed
and a thank you to
@garyo for starting it all
I like to see threads like this about no-nonsense bikes that don't need to cost big money. I'm not familiar with the model, but it looks to be based on the standard welded geometry frame that appeared in the early 90s and was used on many different models. It won't be newer than 1999 if the frame was built in Nottingham, so around 20 years old possibly a bit more.
My advice would be to change as little as possible and don't try to turn it into something it isn't. We are talking about a solid, but basic spec bike, with a strong but not especially light frame. Assuming the existing wheels are alloy not steel, the only things you can really save weight from are the crankset (if currently fitted with steel cranks), and the tyres - by fitting narrower less knobbly style ones. These bikes weigh north of 30 lbs, and without replacing most of the bike, they are always going to stay around that weight. The most important thing is rolling resistance not weight, and a set of 26 x 1.75 Schwalbe Delta Cruiser+ tyres would make a bigger difference o how much effort the bike takes to pedal than changing parts to try to shed pounds off the weight. They are also a lot more puncture-resistant than unprotected cheap knobbly tyres that come as standard fit on this kind of bike.