We stay four days in London, then a rental car to Salisbury and Stonehenge, then a stop in Bath, then Stratford upon Avon a few days, then a stop by the factory for a mini-tour to see where granddad's Morgan was born. After that, on to Wales to visit some old RAF friend and maybe a short ferry and stay in Dublin, thence back to Heathrow and home.
I would also recommend Avebury Henge
http://en.wikipedia.org/wiki/AveburyIt is not so well known but it is larger than Stonehenge and has a good deal of its encircling ditch and mound intact. Best of all it does not have some many tourists and is free. You can wander around and even hug the stones if you so wish. Part of the village is inside the ancient site and you can get a very nice lunch at the pub that is in the middle of the site.
Whilst in that area you may like to visit Moto-Lita / Aviation Leathercraft
https://www.moto-lita.co.uk/our-products/jackets.aspx