hi nigel.. when i was on my way to the UK about a month ago.. i basically just had my CFO sticker on my passport and Xray ready... i also had marriage cert birth cert etc ready just in case they ask for it.. but they never really did ask for those.. just the CFO sticker that the immigration person will look at in the phils and the xray the health port will look at in the UK..
if vimvie is arriving in heathrow.. upon arrival, just ask her to follow the people walking towards the immigration... they asked me to fall in line to the one towards the furthest right... make sure she has her immigration card filled in.. upon talking to the lady from UK immigration she just looked at my visa asked where my husband is.. and just gave me my immigration card back and asked me to go to health port.. upon talking to the woman in health port, she asked if i had an xray ready and i did.. so she just looked at that and asked for my husband's address and checked that on her computer.. and she gave me the sheet back and was asked to go back in line to the immigration desk... so i did that.. and talked to the immigration lady again and she sent me off to meet my husband... hope to have helped!
and yeah like what everybody already said.. get her a coat, gloves, thick socks and a scarf... =)