Tricks of the trade
If the housing market is rising, and particularly if you are a first-time buyer, you should be absolutely clear about the type of mortgage you want before you start looking seriously at what to buy.
In a rising market sellers will be inundated with potential buyers, and will try to weed out the serious from the time-wasters. To give yourself a better chance of getting your dream property you should consider obtaining an Agreement in Principle - this is a document from a lender which effectively says "we haven't actually lent any money to this person, but we would definitely be prepared to lend £x." In other words, an Agreement in Principle demonstrates to a seller that you are both seriously interested in their property, and have the financial means to buy it.
On a more general note it is always a good idea to assemble the various documents you will need for a mortgage as soon as possible. These include three months of pay-slips, bank statements for the last three or six months, and proof of the size of deposit you are planning to put down.