Just a reminder this doesn’t have to be the only purchase proposal we ever do. So if we come to agreement on some things now, we could always make a start buying those bits. I think this proposal is probably already a bigger one than Mike was intending 
So compiling what we have so far that’s not too debated:
Trend Digital Gauge - Amazon - £16.24
Profile gauge/ruler - Screwfix - £10.99
Drill bit gauge - Amazon - £6.99
Screw gauge - Amazon - £8.49
Carpenters Square - Screwfix - £7.99
12" Rafter square - Screwfix - £17.59
Total so far = £68.29
Up for debate:
Moisture meter
Metal detector
Corner clamps
Pocket hole jig
Dowelling jig
Drill press vice ~£30 and/or Quick release bed clamp - £16
2pk Clamping set squares without clamps - Axminster - £26.98
Paint pyramids
Clamps
Equidistant Measuring
Trammel Set (Basically a giant compass)
Dovetail Marker
Track saw clamp separate proposal
Saw track separate proposal
Reciprocating saw already have one
Multitool to be discussed elsewhere
My thoughts:
Moisture meter - I’m not completely againt us having it as it’s cheap, but I agree with Mark, what purpose does it serve other than to tell people their wood isn’t ready yet and to put it back in large storage.
Metal detector - My preference is probably still the Zircon. I’ve had a look through the security ones, and they all have slide switches to turn them on, and they will definitely get left on. V.s. the zircon which is push and hold to use, then it powers off as soon as button is released. It is ashame it doesn’t look like a security scanner though 
Corner clamps - could these be the same as the clamping set squares?
Pocket hole jig - I’ve got 2 proposals for this, both metal. We could go cheap at £21. There’s no width adjustment though, and the clamp isn’t a quick clamp. Or we could go all singing for £64 - this would be my preference.
Dowelling jig - I agree metal is more durable, but most of the metal ones work differently and have several parts, which i think would go missing. The one I linked before is one unit, and the drill holes are metal lined, so my hope would be it wouldn’t get wrecked too quick. For £21.49 I think it’s worth giving it a go.
My preference is the drill bed quick clamp, can do all sorts of timber types. It’d be good to install it on a short chain on the nut to the underside, so if someone removes it, it stays near the pillar drill for others to find.
2pk aluminium clamping set squares without clamps - you can get these from china in 2pks with the clamps for about £20, vs the link you’ve sent which don’t have the clamps included. Or if we weren’t bothered about the clamping aspect, you can get multipacks of plastic ones for £1-2 each (though granted they’re less durable).
Paint pyramids - Might be worth buying bog standard ones to start, they’re about £7 for a 10pk. If we only had the fancy ones, as soon as a couple go missing it’s no use.
Clamps - Sad to hear we have lots of broken ones. Have they failed in a way we can learn a lesson from and buy different? Or is it just the reality of plastic things with moving parts?
I recommend these Sash Clamps. They’re massive, indestructable and come in a 2 pack for £60. They also hold themselves up. Don’t know how they compare to the axminster ones you linked though.