I think the Wessex bunch of monuments would be worth the visit - even with Stonehenge difficult. Avebury would be better, with its associated monuments, the Sanctuary, Avenues and Silbury, to get a sense of the way people used landscape.

Kent has the cluster of Knole, Hever Castle and Penshurst for more recent things. Or you could go to Rochester for the Castle, the Cathedral, Roman Wall and all the Dickensian stuff. (Read Edwin Drood first. Or watch the TV.) Also Baggins bookshop, which is a tiny bit like Hay on Wye.

Penny