Need advice - pay mortgage off or not? And when?

b1234

Hello, can anybody help with some advice?
I have a Co-Op mortgage of £47,700, term left 17 years 7 months, on a discounted rate of currently 4.84% until 20/01/07. Monthly repayments £340, existing overpayment fund of £1150. An early repayment charge of £900 applies until 20/01/07. Property value probably around £250,000 (we were very lucky with the area).
My partner has recently inherited just over £65000. The money is in a Cahoot account, at 4.55% interest.
Added complication: The property and mortgage is in my name only. I am expecting our 2nd child in January and won't be entitled to any maternity pay at all and I have no other regular income (but am still officially employed, going back to work in Feb 2008 with a salary of £23000).
My partner has been paying the mortgage out of his salary for the last 2 years as I have been on extended maternity leave with our first child. He earns just over £18000. Although we are not married we are a commited couple, have been living together for over 10 years, and both see this house as our family home.

What shall we do?

Shall we pay the mortgage off or save the capital as we'll never ever build up such a lump sum again? Or go for an offset mortgage - but will anybody offer me a remortgage deal as I am without income? If paying the mortgage off - when? Now while we would have to pay the early repayment fee or wait until January? What is more cost effective? I asked the Co-Op to work it out for me but they won't.
And finally, how do we go about transfering the property into both our names as this is only fair and needs to be considered should something happen to me. I assume it's easier if I owe the property outright? And will this have tax implications (capital gains)?
Many thanks in advance!