Yeah, solid core is annoying for this kinda work. I accidentally bought a couple of packets of that once from my local components shop, ended up slowly using it up by using it for jumper wires on PCBs and longer pieces to join points on breadboards.
Stranded is the type you're looking for. It's much more flexible. You'll find that the online places like Rapid and JPR are generally much cheaper than Maplins (they charge from 3-15 times more), and BitsBox is good for top ups. A pack of mixed colours of stranded wire should only be a couple of quid, but if you end up doing loads you can save even more by getting one of those bundles of 11 100m reels. I got the second least expensive one on Rapid, the cheapest one has really flimsy plastic and the wire strippers just tear loads of it off!
There are various guages, but I think 7/0.2 is the most common (7 strands of 0.2mm each), but some people on here like to use 14/0.1. I'm tempted to try that out, as I imagine it'd be a lot less likely to tear your fingers up after a few days solid work!