Long post alert!!
As I said before I think honesty and being yourself is the key
Assuming this is a fairly small archaeologically based operation (from what you've said) and that you're probably academically overqualified for it, I would try to be yourself
Although I interview in the NHS, which is a massive organisation, the jobs are working in small teams who have to work together in life or death situations, so I'm looking for people I can get along with - they're all well qualified by the time they get to interview
Certainly the team at Fishbourne Roman P are small and friendly and they would very likely be looking for someone they can get along with first and foremost if employing someone
Unless I'm misjudging the job you're after I would cut your CV to the bits directly relevant to the job
Go to the interview thinking that it would be their loss if they didn't employ you and just be yourself
Generally if you interview enough you can see through the cocky people who have all the answers instantly to hand - you know you'll be sick of them in a few weeks when they actually start work
If I was interviewing someone over 30 I would be much more interested in how they've managed their life as mature adults, and how they arrived at where they are and what they do outside work than what O levels they got aged 16. I often find the best junior doctors are the people who have started as mature students and had to work their butts off just to get as far as the interview.
So to summarise
don't try to twist words that make you feel even vaguely dishonest
Think what an interesting life you lead and what a shame it would be for the company if they didn't employ you
Don't worry about being shy / quiet / appearing nervous - unless you're applying to be the next host on Strictly come dancing this doesn't matter and interviewers will put you at ease
Remember there are lots of jobs around and only one you!
Hope all that helps - it's rather "Unbusiness" but I suspect the worlds of medicine and archaeology have that similarity. I've always been a crap and nervous interviewee and now I'm an interviwer