Yes you can bring a couple of guests.
Parade laps will be at lunchtime - no charge for this but you will need to sign a disclaimer sheet. The stewards will point you where to go when you arrive.
More information is here: https://www.amocracing.com/30-sep-silverstone-national
The Paddock Plan shows where the Aston Martin parking will be.
The Brookland Suite is shown at the bottom of the map. We are in Suite 2A - complimentary tea/coffee/squash and views out over the circuit are available.