English Heritage Membership
If you are interested in visiting a variety of places of historical interest than consider a membership to English Heritage.
English Heritage has an amazing selection of places including Stonehenge and Avebury which it jointly runs with the National Trust.
English Heritage has over 300 listings that are available to visit. While it is possible to purchase an annual membership to English Heritage (£96), they also offer a 9-day (£59) and 16-day (£69) Overseas Visitor Family Pass that can be purchased online. They also run a variety of family events -especially during school holiday periods such as Medieval Fighting Knights at Ashby de la Zouch Castle in Leicestershire to an Ugly Bug Safari at Eltham Palace and Gardens. Check their What's On Calendar to see if there are any events in areas you will be traveling.
Visiting England with the Family using English Heritage
The National Trust offers a variety of family friendly sites from large stately homes to ancient Roman ruins.
Some great places we explored were Beatrix Potter's home and the Giant's Causeway in Northern Ireland.