In reply to Dominicandave:
It is irresponsible, finance is not everything, but I certainly wouldn't be financially crippling myself for this - I see it that 1 - things are very likely to go pear shaped and 2 - you are living for a reason - you are enjoying the fact that you look forward to see her at weekends - without this life may be become monotonus and before you know it, everyone is sick of each other.
Strive to do better, there must be other solutions? Eggs all in one basket are never a good idea, its a bad gamble, clearly only my opinion, but you asked, and I'm half guessing by reading between the lines.
Being separated from her mother in the first place is an issue you seriously need to consider and the reasons why you would be trying to make it a go need to be mutual.
Best of luck whatever you decide.