Interesting you bring this pointer up. Only yesterday I was having a very heated debate with my MD about this.
He says that the way forward would be to borrow the cash now and go out and buy a house as they are only going to go up (they are starting to around here anyway). His point was that my goal is to save up £15k (10%) by May next year, however if the prices rise then that £15k will then need to be £16k then 17k etc etc. Which would then make something that is achievable, impossible!
There are some absolute bargains to be had at the moment, i.e. a house is up for sale for £150k, needs some work doing (pretty much everything, no central heating!) however the houses next door are worth £225k+), this makes the loan idea really really tempting.
On the other hand, the mortgage will already be enormous at around £800 a month, adding a £230 - £250 a month loan repayment will eat into the life style and also eat into free cash to do the house up.
It is your decision, if you can afford it and there is a house you have seen go for it, then in 5 years when you come to re mortgage just repay the loan and add it onto your mortgage.
I however (well my gf!) has decided to do it the 'cheaper' way and save up for the deposit so when we move into our 1st home we will be 'debt' free.
Edit: As for a loan effecting your application, a friend of mine went and got a mortgage with Natwest, they still went on how much you could afford to pay back rather than income x whatever. So £4k coming in between 2 people, after bills and mortgage & loan there is still a fair amount left to splash.