I know this is a thread about a dog crate for an airplane, but I'd like to offer a bit of advice to mariefer (if that's ok with you, cujodu).
Mariefer: I'm unaware of restrictions on flying to the UK, but like you said, it'll probably help some if you could fly to the States with your pet in-cabin. The airlines that I came up with when looking into this a few weeks ago that accept pets in-cabin to the States are: Avianca, Delta, NWA, TAM Brazilian and United.