If you re planning to visit lots of historic places, gardens etc you'll probably find it better value to buy one of the passes which are available to overseas visitors. Decide where you want to go and then pick the best pass to suit you. Have fun!
English Heritage - Pay only once and enjoy unlimited admission to England’s greatest historic attractions in the care of English Heritage from only £19. Free entry to over 100 historic monuments, reduced entry to loads of events and a free 280 page colour souvenir guidebook including maps and information on a further 300 free sites in the care of English Heritage. Available for 7 or 14 days and for one adult, two adults or families of up to six, this tourist pass costs from just 57p per person per day (based on family 14 day pass).
Great British Heritage Pass - For any of you garden lovers or those planning a history or heritage themed trip around Britain, the essential "buy before you leave" product is the Great British Heritage Pass. Providing free entry into over 600 castles, gardens and stately homes across the length and breadth of Britain, it really is the key to unlocking Britain's secrets and is available for periods of 4 days to one month.