Do the sum
Two sites can be cheaper as singles.
A London pass for several attractions in a few days — only cheaper if you will actually go in.
Go City sells all-in attraction passes for London (and other cities). From Frome that means a Trainline ticket plus two or three big sites in a weekend. If you only want the Tower, buy a single ticket on Tiqets or the official till.
The maths is on their site: pick the attractions, see if the pass wins.
We do not guess a family itinerary.
Best for: A packed London weekend
Shop type: Multi-attraction pass
What to weigh before you click through.
Two sites can be cheaper as singles.
Frome to Paddington, then the pass.
Longleat is not on a London pass.
Single museum tickets live there.
Same click-through idea. Official shops only.