Apart from photos/current passport we only need to send in the one page where we (and the countersignatory) fill out our details and sign, right? All the other pages - including the ones with a summary of all the personal details - can head straight to the shredder?

Yes.

I can just send my current Australian Passport as is, can I? I don't like the thought of photocopying the entire passport, so much wasted paper.

Also I'm a bit weary of sending all these important documents overseas :S

If you want to include your Australian passport then just photocopy the bio-data page.

I was under the impression I had to provide my current passport including blank pages?

From this page: Uncancelled non-British passports: Please send us a colour photocopy of your non-British passport (every page including blank pages). We retain the right to ask for the original passport. We will let you know by email or post if we need you to send it to us.

In theory, yes, in practice, not so much. Did you provide an Australian passport the last time you renewed?

This is my first adult passport. So I can send a colour photocopy of the bio page and if they need more they will contact me?

Honestly, its up to you. There is a similar discussion running in the US forum at present, and I've seen it discussed often over the years. A few people send their foreign passports - but that can cause issues as you then can't travel, have no ID etc. Some send the bio page,as you suggest, and have no problem. Others (and I admit to falling into this category myself) accidentally tick the wrong box, forget that they have not put the other passport into the envelope and just don't send it - no problems there either

Thanks for the insights! I'll go with the colour photocopy, but I'm happy to send the passport if needed, I have no time to travel for the next year and a bit anyway!

Just causes a major issue for people like me who have no driving licence! That passport is my only ID

That's fair enough. Would getting a Keypass ID from Aus Post help? Seems to be marketed for people without driver's licences.

Not really worth it now I have the two passports, I'm used to carrying one everywhere! The only option when I came out years ago was something similar that Qld Transport did but they calmly told me that I was far too old to have one and should just learn to drive instead Hence I've just become permanently attached to my passports

I had the Aus Passport pages copied but forgot to include them for three passports. New British passports arrived with no issue. This was in the last month.

Reporting back that I sent my documents on the 1st of December and received the new passport and documents back on the 21st of December.

I too was worried about the time when applying to the UK but was very impressed with the reaction time (a little over two weeks)