For a trip in May and June through the English and Scottish countryside, are hotel reservations far in advance necessary? It would be nice to be free to explore without being locked into a pre-planned itinerary.
If your expectations and budget are flexible, you can probably do as you wish.
The choices a day or two before are going to be more limited than what would be available 2-3 months ahead.
I've done this on numerous trips to Europe. I use booking.com and book a day or two ahead based on weather and things I hear about on the way. As long as you're not uber-picky it will work just fine.
The final week of May is a school holiday so it’s a very busy time.
Other than the Bank Holiday at the end of May, which will be busy, you should be ok booking a few days ahead online. Popular places such as Skye will need to be booked now, if there is any availability left. The Lake District will also be busy.
Planning for your trip, booking hotels or B&Bs, tours, your rental car helps you to determine where to go and what to see. Also, it is insurance that you won't have a problem finding a place to stay, etc.
We did a 28 day drive tour of Wales and England in 2017 and planned every night as well as what we wanted to see.
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