£20k Deposit?
I think that this is the media oversensationalsing something again. You will need somewhere around half of that, I think - even for a 95% mortgage.
However, even £10k can be difficult to put your hands on immediately...particularly when renting is not very cheap either, thuis making it difficult to save.
The other difficulty for first time buyers is that the market for that type of house (smallish, maybe two bedroom semi/appartment) is always going to be buoyant as the demand for such properties is always high. As such, even when the market is on a downward trend, the prices of these houses don't move very much at all...so they remain excessively expensive for any couple who are not on very much above average salaries.