In reply to SambucaHughes:
My thoughts. If you plan on keeping car a good while longer and if rest of exhaust looks iffy you might be as well getting it all replaced now. Saves it dropping off at an inconvenient time and you get a longer warranty on 'full system'. Full system usually means everything from catalyst back... i.e. whatever drops from engine and bends under engine (front pipe) plus catalyst section excluded. That area tends to last longer as it is warmer and drier there (I think) but it can be vulnerable to the engine moving slightly on its mounts and often has a flexible joint which itself sometimes gives problems.
Replacing a section yourself is cheap and technically easy. It can however be an utter ball ache of a job with rusted up bolts, things snapping or damage occurring in other areas as you work. If you have access to another car its worth trying to see if you can dismantle then getting the replacement bits. If you can't do it or get part way and stuck nothing much lost.... you can then get to garage/fast fit place with it and not have a bunch of parts they may not want to fit for you
If its a hole in the catalyst pipe/pipe with DPF in it that's where an independent garage may do a repair - welding a section in. Welding an exhaust is tricky as you can easily burn holes where they shouldn't be - many main dealers don't do this sort of work as its time consuming and risky - they want to simply replace everything - a decent independent will do it if it stacks up cost wise... i.e. the labour and time makes sense vs not replacing an otherwise ok and costly bit.
Finally, for old and common cars your big fast fit places are actually pretty good - its their bread and butter... whipping a dodgy section out and sticking a cheap after market replacement in is core business for them and they tend to charge a fixed price irrespective of whatever difficulties they may have actually doing it. A garage tends to charge by the hour so if they have a mare of a job you may well pay more.... Most of the horror stories about fast fit are low quality work on more complex stuff and grannies being conned into having way too much work done. Go in needing a simple job done and there's not much they can get wrong or rip you off over. Phone for quotes and go to cheapest or get the closest place to price match the lowest quote. Look up a parts diagram so you know which bit is needed and take it from there... and if they recommend doing other sections at the time take a view (car up on ramps) on whether their recommendation seems reasonable or chancing it....
I have had OK results with the type of repair which is a flexible metal sleeve type thing that jubilee clips around a hole but in my opinion, more often than not if you have a 50p sized hole the rest will probably fall to bits soon so that sort of thing is more a case of putting off the inevitable for a while or 'hiding' an issue while trading car in or whatever.