Hi Off Topic.
A suggestion- BA have World Traveller Plus seats which are a premium economy class. They offer more leg room than World Traveller (economy) and are not as plush as Business.
Personally I do not like the new BA Business class with the head to toe twin seat arrangement.
They are the ones I would go for- Business is not worth the upgrade to me if I'm paying and I'm 6' 2" tall.
By the way, US airline's Business class is more akin to World Traveller Plus than BA's Business class, at least according to Mrs Jezer who has more experience of these matters.
Regarding Stonehenge, prepare to be disappointed. That sounds dramatic, and you may well prove me wrong and find it fantastic.
I am from around there and used to love it until it got enclosed in fencing and barbed wire. The visitor facilities and car park are third world and the place is a national disgrace. New facilities are to be built around a mile from the main stones and the old facilities and indeed the road that goes nearby are to be removed, but that won't be in place for next May.
If you were to go, and I'm assuming you're taking a day trip by train from London, then go to Salisbury and visit the wonderful- no- fantastic Gothic Cathedral with the tallest spire in the country. The Cathedral Close is so beautiful and is the largest in the country.
Oh- while you're there come and see me at the Stately Home where I work just down the road. You want history- you'll get it!
(PM me for details if you wish).
As for Bath, you could fit in Salisbury (take a bus to Stonehenge if you want) and then the train heads straight on to Bath around forty miles away.
It's great from a Roman as well as a Georgian point of view. The countryside around there is also lovely.
I can't comment on Hastings or Cantebury from first hand experience, though I'd say there is little to see at the former and the latter is magnificant.
Hope you have a great time in the UK.