Mortgages in principle
Getting a mortgage and buying a house are usually very much intertwined.
When you find a house, you'll probably have to move fast to secure it. To prevent being delayed while sorting out a mortgage you could first get a "mortgage in principle".
Having one means you should be able get the actual mortgage quicker when the race to buy your chosen home begins.
A mortgage in principle is a conditional offer made by a mortgage lender that - provided the information you give them is correct - they will "in principle" give you the loan you have discussed with them.
Knowing what you can afford will also help you narrow your search.
It's very useful to have one before you even start looking for a house to give you the edge over any competition.
You can get this offer in writing to show to Estate Agents and sellers who will see you as a serious prospect.
To get a mortgage in principle you have to go through the same motions as an actual mortgage. That is: Consider what type of mortgage do you want and then find a mortgage lender you feel can offer you the best deal.
It's only when applying for the actual mortgage that the mortgage lender will want to see the proof of your income etc.