I have a few bits of advice, as a poor student who tends to go through bikes quite quickly.
Pedals are a personal choice thing, decide what type of pedal you want (i.e. clips and straps, clipless, or just flat pedals)
Headset locknut- eBay is your friend. Or your LBS. Or this forum.
Chain - KMC S1 if you're on a real budget. I think they can be had for around £4 these days.
Leather saddle- If you can splash the cash, Selle San Marco or Brooks are good starting points, though you're probably looking at £40 upwards for this.
Handlebars are again a personal preference. I assume that you already have an old-style stem that fits this frame.
You also probably want crank bolts, as you suggest the old ones are mashed.
I have a few bits of advice, as a poor student who tends to go through bikes quite quickly.
Pedals are a personal choice thing, decide what type of pedal you want (i.e. clips and straps, clipless, or just flat pedals)
Headset locknut- eBay is your friend. Or your LBS. Or this forum.
Chain - KMC S1 if you're on a real budget. I think they can be had for around £4 these days.
Leather saddle- If you can splash the cash, Selle San Marco or Brooks are good starting points, though you're probably looking at £40 upwards for this.
Handlebars are again a personal preference. I assume that you already have an old-style stem that fits this frame.
You also probably want crank bolts, as you suggest the old ones are mashed.