if she will be 12 this month, then thats another reason to get her here ASAP, because she will be going to start secondary school here, when all the other 11 and 12yrs old start, if she starts next year all her class mates will have known each other for a yr.
are you on speaking terms with her father?, is he ok about her coming to the uk? would he give his written consent ?
if you left her for a year in the phils i wouldnt have thought you would have a problem with sole responsibilty if you supplied evidence,(as long as she was not left with her father)
has your daughter always lived with you ?
£3,000 should be enough for you both, but remember you need money for the visas, money for air tickets, money to pay for a wedding