Tim has some suggestions in response to an emailed plea on the same subject:

Hello,

A grandstand ticket would be your best bet.
I think I was at the Woodcote grandstand when I went in '99.
That's a good one, as you see the cars coming out of warp at the turns
near Luffield, and accelerating off again down the straight at
Woodcode. You might also get to see a bit of overtaking there.
Perhaps.  This is F1.   :-) 

I bought my ticket through some pals in Bristol who'd just set up a
Corporate Hospitality firm.
It covered the whole weekend - practice and race day.
Bit of a strange situation, as I was a party of one.
That confused the hell out of the hosts in the tent.   :-) 

The other people on my table worked for British Gas and had won the
firm's raffle... or something like that.
As I set off for the grandstand for the start, they decided to stay in
the tent and get stuck in to the freebies.
I remember being amazed at the time, but I suppose they weren't
enthusiasts like the four of us!

A pitlane pass is a great idea.
It's difficult to describe the sound of the cars starting as you
stroll along there.

On the race day itself, you can get a little disorientated if you are
trying to follow the race as it unfolds.
A bit like sitting on a motorway pig perch as the cars whiz by.
It might be worth bringing a small radio and earphone for some commentary.
I brought a small LCD TV so that I could keep up with the race on ITV.   :-) 
I should have consulted it when Schumacher crashed and broke his leg.
We all thought he'd just stacked his Ferrari, and were cheering loudly.
The commentator on the PA took a dim view and told us off...   :-/

Getting there can be fun... not sure if it is best to drive up.
The countryside looked a bit gridlocked to me on race day, but maybe
it isn't that bad if you set off early.
I was staying overnight in Northampton, so I got a local cabbie to
take me there through the B roads.
Even then, he could only get so far before advising me to walk the last bit.

Tim

(Published with his permission)