andygo,
I was told my many (qualified/ technicians and non qualified enthusiasts) not to worry about my suspicions that something timing chain tension related was wrong on start up. The car was VW warrantied to the hilt with roadside assistance too and I'd been told by VW warranty/ the supplying garage that if it failed I'd be covered... so 'stop worrying and just enjoy the car.'
How can you though? My logic was to question, surely people can't want to risk the significant cost of failure and catastrophic consequential damage, notwithstanding the cost of courtesy car supply etc when for a few hundred pounds, many thousands of pounds will inevitably be saved?
So I pursued it and helped by the very knowledgeable Rocket Ross from this forum was supported to speak from an informed position. The aforementioned RR actually felt that our "rattle" might be indicative of a failure just weeks away and yet VW personnel were dismissive of my concerns.
The dealer agreed to review the position, they agreed they could hear the rattle and on stripping things down, different technicians agreed that the timing chain was also visibly slack. Everything was replaced 'under warranty' immediately.
I've read (and no more than that) that 'a cheap fix' or a 'keeping the wolf from the door' fix is a fully synthetic oil change which can in certain cases, help. It wouldn't convince me though.
Not a clue about the rocking the car scenario but in the absence of a sympathetic mechanic being able to supply and fit tensioner and related parts before your departure; or if you have no warranty/ breakdown cover, it sounds like "will it hold out, won't it hold out" car thoughts might dominate your thoughts...
Unless your son will swap cars with you and gets yours sorted whilst your away