Need advice on mortgage deposit and investment decisions

saxophonephil

Hi all, I am turning 26 soon, live at home, salary £33.6k and this is my current breakdown of savings:

£24k in cash, £9.5k in Lisa & £31.5k in Index funds (Mostly S&P500, overall 75% US stocks)

I am a long term planner and my goals are to have a large investment pot in 20-30 years while simultaneously looking to get on the property ladder with 1 bedroom flats costing 150-160k in my area. Whilst it is clear that with the LISA and the cash only I could afford this with no issues, I am wondering whether long term it would be wiser to:

1. Maximise the deposit and drain out the index funds, and start investing again regularly after property purchase.
2. Leave the index funds where they are untouched and just use my cash and LISA for the deposit?

Some additional context - The original cost of my index fund was £32,000 but with the current state of affairs that's now worth £31,500. Additionally, I suppose with more deposit I could stretch out for a more expensive place, meaning a higher probability of a greater house price increase over time etc. but this would come with the opportunity cost of starting my investments from scratch and obviously I can't predict which option will make my net worth "better off overall" long term. Appreciate the help!

ACG

This is probably more for an investment question than a mortgage one. 
On a side note though, I think houses are generally better investments than flats - you will not have service charges, reducing years on a lease etc. But I only mention that in case you seen your home as an investment. 

My first home made about £12k a year, my current home has "made" about £25k a year in the last 5-6 years.