Firstly, if this is the wrong section, apologies.
Second, I probably sound like a stereotypical northerner 
We are a family of 4, teen DC (so adult pricing applies). We decided as a family to split our holiday this year. Lucky enough to be picking a subsidised trip abroad, due to a client of DH being exceedingly appreciative of his level of commitment to their company over the last year.
So, as we only have to pay flights for this holiday, we decided to take the DC to London for a few days. I really want them to experience the city, take in a show, see the sights, visit the Natural History museum etc. DD and myself have been before and she loved it.
We a restrained to school holidays, but not particular holiday, so flexible in this regard. Just a bit 
at how much an apartment, train fares etc would cost, before I even factor in travel, food, and activities. Budget is reasonably flexible, especially if we go later in the year as I can budget a little more.
So, at the risk of sounded extremely daft, can we, as a family of 4, do London 'cheap'? Is it a case of planning well?
Or do I sound stupid?!!!
TIA