If you are looking for finance / mortgage there are a couple of companies that will deal with GA, i.e. Close Bros Aviation.
These companies have a minimum lend of somewhere near £60,000 and require a deposit of around 25%... so you aircraft new or used would need to £80,000 and up.
The other way to do it is remortgage your house and pull some equity out of it, which isn't the easiest thing to do and more (or the most sensible !!)
Hope that helps