As a FTB and from the limited knowledge I now have . I guess with both options I still need to pay legal fees for conveyancing as well as getting a survey done on the house.
With the mortgage route this can potentially take 6 to 8 weeks with a potential product fee of £1k
The loan would be instant, more flexible but I’d potentially lose £2.5k ( you could argue only £500 of this is my own money)
The interest rates of 2 per cent on a mortgage over the term Versus 3.5 per cent on a loan aren’t a big issue for me as this will be minimal.
So I guess the mortgage route is the most cost effective, just a bit more drawn out
Personally with the bonus you get from the LISA, you'd probably be better off getting the smallest possible mortgage you can find. Which may mean not needing to put down the entirety of your 20k deposit.
How does this right to buy discount work? Does that contribute to any deposit you have. The 70% discount already knocks you way into the lowest LTV tier, so in theory you could stump up a fiver and still be in the lowest LTV tier.
Edit: Reading into this a bit more, i think you'll actually struggle to find a mortgage for such a small amount, there's such things as offset mortgages, but i'm not sure how that would work with your deposit.
From everything you seem to have told us... The house has a value of 100k, you're likely to be getting about a 70% discount (70k), you have a 20k deposit saved up, along with an 10K LISA (7.5k cash value). If you withdrew the money from the LISA, you'd only need 2.5k remaining to fully pay off the balance.
How long realistically would it take you to save 2.5k? If we're only talking a couple of months, and your credit rating is good, you could get a 0% credit card and pay that off over time. A loan of such a small amount normally gets stung with higher interest as banks are typically more interested in loaning much higher amounts. The lowest i could find was 13.5% APR.