I live and work in the UK, and am starting to look seriously into buying my first house. I have thought about looking to buy a few times over the last few years, but ended up deciding not to for various reasons.

Having had a cursory look at properties on rightmove, just to get an idea of what's available, and roughly how much a property that fits my requirements is currently being sold for, I then had a quick look into mortgages, to see how much I could afford to borrow. The Loan-To-Value rate I was quoted at one mortgage broker was roughly 65% (for a property at the upper end of what I had looked at).

What I'm unsure about, is how to decide how much I should stump up for a deposit towards a property... According to an article on Which?, (July 2019), you'd need at least a 5% deposit to get a mortgage in the current market, but the average deposit in the first half of 2018 for first time buyers was 16% of the property value.

I am in the fortunate position of having been able to save a large percentage of what I've earnt for a good few years now, and could realistically put up to ~40% of the property value down as a deposit (for properties at the higher end of what I'm looking at)- which ties in with the LTV rate I have been quoted.

But since this is at the higher end of the value of properties I am looking at, I obviously could consider some cheaper properties, for which the deposit value I have would be a greater percentage.

All of this is obviously while ensuring that I have something set aside as a 'rainy day fund'.

How can I decide what my budget should be? What are the factors I should be considering in this decision process?