Thanks. I live in a small flat but could do some basic bike maintenance on the landing, if I had to. I don't really know what the tools are that you mention... I suppose if anything goes wrong with the chain then I'd have to fix it myself as, if the bike is non-functional, it would be difficult to get back to the shop. What do you need if, say, the chain comes off when out riding? Also what would I need to do puncture repair? I think the current tyres are Giant S-X3 Puncture protect, 700x38c.
Louise
I've only helped others who have had a chain come off, most usually the root cause was that the gear limit screws are way out of whack, allowing a derailleur to travel too far one way or the other. The chain then jumps off during a gear change and it sometimes jams between frame and front sprockets, or between rear cassette and spokes / frame. The first aid fix is just some brute force and a prying instrument of some sort (multitool is good), that usually frees the chain, then put the chain back on the sprockets and keep it in a mid range gear until you or a mechanic can do the gear re-indexing at the next opportunity.
The chain can also just simply break / snap, that's pretty rare though. To fix that you need a quick link (a link of chain designed to replace a broken one), and a chain splitter tool.
On puncture preparedness, you need a spare tube of the correct size, something to inflate with (CO2 or pump), tyre levers, and most of us carry some glueless patches (or old school patches and glue) as a back up in case you get more than 1 puncture (or you pinch the new tube). The key thing is to learn how to fix a flat before it happens (Park Tools' Calvin does two excellent videos on it), and please practice the process before you need it as it takes all the stress out of it. A warm front room with Youtube on your TV and a cup of tea in hand is a far better environment to learn in than a windy, dark and wet country lane in February. Being practiced at changing tubes will have you on your way in 5 minutes, being unsure of what to do could leave you cold, wet, vulnerable, and with fingers that can't feel anything.
View: https://youtu.be/58STtUM-Wow
View: https://youtu.be/T0F_hibWHlU