Springbok,
Bu115hit regarding the checking of supermarket loyalty cards etc! My daughters continue to use mine in the UK.
yes you should keep flight ticket receipts or stubs but what does it prove if you omit a stub? Nothing. They have the ability to check your passport details and entry exit through immigration.
A certain amount of the procedure is based on honesty, if HMRC think you are now being honest, they will investigate but also ask you to prove you were resident outside of the country for the period claimed. It will be up to the individual to prove it otherwise HMRC can interpolate what they think is the period you were in/out of the country.
As for family staying in the country, it doesn't matter. I am in the Middle East with my wife, my daughters remain in the UK and are tax payers in their own right. I pay no UK tax at the moment. What I do pay will be calculated when I return to the UK.
Advice regarding talking to HMRC is good, I did and they were more than willing to tell me what and what I couldn't do. Sent me all the information and a P85, send me regular letters to my address here (another way of checking you are still there).
My advice, talk to the tax man direct, don't lie because he will hammer you if you get caught out. PPRUNE is a rumour network and there is a lot of bad advice given on here, talk to the professionals!