Early remortgage for a buy to let

Hi all,

In jan 2012 I bought my house for £160,000 with a £40,000 deposit.

My dad has recently inherited a house worth £200,000.

His brother wants to sell his half, but my dad wants to let it.

I am going to look into buying out my uncle so that me and my dad will co own the property.

I'm a year into my two year morgage term.

My question is, can I remortgage mid term to realise some of the 40,000 I put into my house in order to fund it?

And...

What sort of deposit would I need to buy half of a second property ?

I goimg to look into this properly this week, but wondered if I could get some advice here as well ?

Thanks
Brett