Steve,
Back saws get used for cutting smaller stuff to length, trimming excess from plugs and dowels before paring, but primarily for joint cutting. One you get in the way of using them, and especially cutting to a line, they can save all sorts of time and you'll wonder how you managed without. Something like this Japanese
Doutsuki-me from Axminster would be just the ticket for all sorts of work at the bench. You'll need to make a bench hook to go with it; one that hooks over the back of the bench to allow for the pull stroke rather than the traditional western style. If you'd feel happier with a more familiar western saw, I wonder if the
Axminster Speed Cut tenon saw might be an economical starter? The blurb suggests it's ideal for the beginner. I'd be hesitant to suggest you spend too much on something fancier, despite the cry once philosophy I normally subscribe to, because it's perfectly possibly to make a pig's ear of saws when you're starting. DAMHIKT...
I use block planes for much the same as Tony says. Especially trimming end grain, just rounding edges (so much quicker and with less potential for disaster than a router) and general "I just need a trifle off there" work. A low angle type is the way to go, 'cos it's particularly suited for end grain (which is most problematic to plane) but can easily be used for long grain too. Two possible routes, depending on your budget probably. A low angle with an adjustable mouth - being able to have a tiny mouth opening while taking fine shavings is a big advantage, but less so on end grain - is the most common route. Something like the
Veritas for instance, which are really ideal for the novice I think, with good instructions (no, they're not paying me - honest!). Avoid the modern Stanleys and Records if you can afford to, because you won't know what to do to make it work as well as it should, which is really disheartening. The alternative is to splash out a little more and get the
L-N rebating block. Not just 'cos it's on offer at the moment, but because owning a plane that has a blade that reaches right across the sole is very handy. Why? Because it'll plane into a corner. If you want to trim off a trifle from your tenon cheek, it'll do it, while a standard block will leave, at best, a ridge in the corner. Ditto if your rebate's just too shallow. But you can still use it as an ordinary block plane. Well worth consideration I think.
Chisels you have, so I'd hesitate to upgrade them
just yet. But can you sharpen them? Even very lowly chisels will make you go "Oooo" if they're sharp. If you can take Tony up on the offer and get him to show you how to sharpen, that'd be worth its weight in gold. Cornwall's a bit of a way away, but if you're down here you're more than welcome, although I'm totally Kity-less I fear. In fact I wonder if I have a chisel handy I could sharpen up and send you... I'll have a look. PM me if you'd be interested. I don't know if there'd be any interest, but one of these days I keep meaning to do a step-by-step, fully illustrated "how to sharpen simply" guide. Where are the Tuits?!
I've never got on with a #5 myself, but it is the general all-round size usually recommended. Again, if you can get a hands-on demo of how to sharpen, adjust and use it, that'll make a whole heap of difference. In lieu of that,
Jeff Gorman's site has a wealth of solid info on the subject. Don't worry if you get confused; come back and ask and we'll be happy to try and clarify anything. With pictures if necessary.
I hope that helps a bit. As I say, yell for more details as required. It's tricky to keep it simple, but also not to leave anything important out!
Cheers, Alf