Five days in the UK

This is NOT a long time, but we plan to make the most of it! We were last in the UK in 1994..whoa...long time ago. Then we travelled with two very young children, so this time it will be totally different. However..where to go? We fly to Heathrow early in the day & thought we might hire a car from the airport and head out into the countryside for three nights, then back to London for the last two. Due in Paris then, but can take our time that last day. Paris isn't far after all! Now decisions to be made...B&B's ??? Cottages???? Hotels???? Where???