Action Fraud has issued a warning about these scams http://www.actionfraud.police.uk/embassy...
The US Embassy has issued a warning http://london.usembassy.gov/cons_new/acs...
The Romancescam.com site has issued a warning http://www.romancescam.com/forum/viewtop...
Romancescams.org has issued a warning http://www.romancescams.org/TypesOfScams.html
In fact there are thousands of warnings about this scam online. There is nobody in love with you and coming to visit. You have been scammed by some teenagers in an internet cafe in Nigeria using stolen photos trying to con you and the 50 other people they are talking to into sending money
'Heathrow airport' doesn't ask anything. UK immigration based at the airport (among other places) may ask for things like evidence of financial means to support yourself, confirmed return ticket, etc. But as per earlier answers, this BTA thing is almost guaranteed to be a red flag for scam of some sort.
BTA or Basic Travel Allowance is a term which only exists in the vocablurary of scammers.
No. No such thing. It's very easy to look up by yourself.
No