have received conflicting advice , layover visa in transit

Dear friends ,, have received conflicting advice ,
flying virgin frm delhi tlli heathrow 20 hrs stopover ,,then virgin to JFK . travel guy says no visa required fr transit of less than 23hr period can go outside fr sleeping return in morning board and leave fr usa , however another fellow says can't move out of airport ,unless valid UK visa is there . pl HELP , otherwise with toddler gonna go berserk .
also is there heathrow airport hotel which will be ok fr sleeping over and don't need visa
UK agency phone number will be appreciated if available ,tickets all done now
pl post it in uk forum if need be
thanks again

http://www.ukba.homeoffice.gov.uk/visas-immigration/transitthroughtheuk/visa-to-transit-landside/

Especially the "Transit without visa' concession" section

Official UK govt information: http://www.ukba.homeoffice.gov.uk/visas-immigration/transitthroughtheuk/

Assuming you're Indian (you don't say for sure)...?

... you would need a DATV if you only want to stay airside - see http://www.ukba.homeoffice.gov.uk/visas-immigration/transitthroughtheuk/visa-transit-airside/.

If you want to go find a Heathrow hotel, you'll need to clear immigration and for that you'll need a VIT, so see http://www.ukba.homeoffice.gov.uk/visas-immigration/visiting/transit/

You need to state your nationality if you are asking visa questions.

The above sites shold have all the answers though.

Thank you wondeful people for replying ,, Yes Indian national . with usa visa 10yrs
but no current . uk visa .
just taking the kids to orlando fr summer
thanks again if any phone number for uk immigration available will be appreciated .The uk embassy here is completely unhelpful

Seriously, just read the website, all the info you need is there.

(Personally I'd have taken them to Disneyworld HK, easier to get to from India).