Some ideas for hotels on a budget.  You will need to go online at www.laterooms.com to see what suits your budget but here are a couple of suggestions...

If you want to bring the car then how about Brentford or Ealing.  if you don't know the area then it probably sounds daunting but here's a couple of ideas for you.

Holiday Inn Brentford

It's a 20 minute drive to Kensington or a couple of minutes drive to Boston Manor Tube.  On the Picadilly Line it's 20 minutes to South Kensington with no need to change lines... it's just a short walk away to the studios from there!  Perhaps the husband wants to play a round of golf on day 1 or 2 before attending the final day?  I can recommend some local courses if you like!

£80 per night for room with 2 double beds based on 2 adults and 2 children.  There is a £12 charge for parking

Ramada Encore London West

Hotel is 5.3 miles or 13 minutes by car or so Google map says!  Parking at hotel is £10.95 per 24 hours but certainly an option to look at if you are coming by car and have a driver who is willing to take you to the studios each day.  Price ranges from £79-£109 per night for 2 adults and 2 children.