We (husband and wife) walked the 102 mile Cotswold Way in seven days, averaging about 15 miles per day. It is a perfect walk in many respects...scenic, bucolic without being isolated, and challenging in parts without being unduly strenuous. We chose to wing it...we each carried a small pack (which had everything we needed) and did not book rooms in advance. This allowed us flexibility...we could walk further some days, shorter others, and stay at inns/B&B's that appealed to us. Research in advance (there is a great Cotswold Way website) gave us a good idea about possible accommodations. We used the Cicerone Guide, which has a map in it; missing a turn occasionally and getting temporarily lost happens, but in a way that makes it more exciting. There are tour groups which will book your accommodation in advance, transport your (unnecessarily) bulky luggage, etc.; many prefer to do it that way.
Bath, at the end of the trail, is a nice place to relax for a day or two...the baths/showers/spas offer a great relaxation opportunity. There are some good restaurants and shops (aqua blue glass is a trademark of the area). London is only about two hours by train from there. TIP in Heathrow: stay at the YoTel in the airport, for convenience and price, if you are flying from there.
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