Want Audi estate for my wife -- please advise

[notorious]

Team,

I've never been on car market since 2010
And it looks like I miss some important wisdom here

It is time to get "estate" family car for my wife
(ideally in "women's colour", i.e. lipstick red)
Budget £10k+ or so

1. want Petrol
2. want Manual
3. want low RPM on highway speeds for good noise comfort
4. want simplicity and something that will last forever if maintained properly

Would happily buy just another D2 FL 3.7,
but they are not available with estate chassis & manual
(my A8 3.7 makes 1.5k RPM @ 70mph @ 5th gear, which is absolutely superb)

Interestingly, don't see many A3, A4 and A6s on the market with 1. large displacement naturally aspirated petrol engines 2. with manual
It looks like v8 and v6 engines are only found in S- or RS- series, but those won't satisfy my 3rd criteria since they will rev like crazy at motorway speeds.

Please advise what I should look at -- I will welcome all your comments!

Also, where should I search for used cars sold in the UK?
(I have only looked at autotrader.co.uk and cars section on eBay)
What's the ultimate place to find great stuff these days?