The short answer is that if the AdWords bid value is £1 then you will not get £1 per click on an ad.
The bidding process is complex and depends on numerous factors, many of which are not publicly known.
Yes, mobile ads may be lower than desktop, but the converse could also be true.
Regardless, whatever the advertiser actually pays for the click, you will only see £0.68 if it were £1 because Google take the other £0.32. That's the publisher cut of the click value.
The ads which are displayed on a particular page will often be different to another....