Stonehenge and Salisbury Cathedral

If I understand your time line correctly you have three nights which means two full days. Since the tour you already have booked is for the first full day and includes Avebury I'd definitely keep it. Avebury is completely different than Stonehenge and well worth seeing. If your primary interest in Salisbury is seeing the cathedral, consider getting an early start to Salisbury on the second full day. You may be able to check it out and then return in time for some exploring in Bath. Then on the departure day, leave the bags at the hotel after check out, explore Bath, and then head to London in the late afternoon.

I'd go with C but TC's suggestion is a close second. I'd hate for you to spend 2 hours on the train on your full day in Bath going back and forth to Salisbury.

You could also change your reservation to spend night 3 in Salisbury instead of Bath. You could spend all day in Bath on your 2nd full day then transit to Salisbury in the early evening. Then spend most of the next day at Salisbury Cathedral traveling on to London at the end of the day?

Where do you arrive to Bath from?

I concur that you shouldn't cancel the tour since it allows you to see Stonehenge, Avebury etc. The driving or public transportation connections would be a headache if you tried to do this on your own from Bath.

If I understand -- and as the other comments indicate -- the Mad Max tour does not give you time in Salisbury, and that's the thing you're concerned about, is that right? As suggested, spend your 2nd full day exploring Bath, then take the 3rd day to go to Salisbury and see the cathedral. If you can cancel the 3rd night of Bath lodging and sleep in Salisbury instead, then you'll avoid having to backtrack to Bath.

Based on the valuable input, we are thinking plan C: Day one tour, day 2 explore and enjoy Bath, day 3 check out as planned.
We arrive in Bath after three weeks in Ireland and Scotland. That morning train to Salisbury and after a leisurely time in the cathedral and lunch, train on to London. We are inspired by A Sense of the World, my pianist world traveling grandmother, and all caught up in the joys of winderlust. Thank you,

I would pick Option C. You don't say what time you are needing to be in London. If you are only to stay in London for a flight home the next morning, then I would head out of Bath early (after your third night) and go to Salisbury on the way to London. I would not cancel the Madmax tour and you will be disappointed if your short change Bath. My nephew lived in Salisbury for a while and I happened to be passing through on a visit to Downton Abbey one summer. We did a slow drive-by on Stonehenge for pictures only and ended up spending a lot of time in the Cathedral. We were not disappointed. Sometimes you just can't see it all!

Margaret

Enjoy Bath, it is great.

I would go with C

Avebury is worth a visit, as are Wells and Glastonbury south of Bath.