So... the amount advertised on rightmove is probably under the home report, and under what they actually want for the house. That's right, isn't it?
The amount on Rightmove is the price at which they expect offers over to be made. E.g. price is £100,000 - they expect offers over that amount. If the going rate locally is to offer 10% over then you will need to offer £110,000 to secure the house.
The exception is where it is listed at a fixed price. Then its the first person to make that offer who gets it.
So then how do you find out what it's actually valued?
The valuation will be listed in the Home Report
Do they already have a home report or do you need to get your own
All vendors have to purchase a home report which is available to all buyers. There is no need to get your own one done.
What if it's valued by your own less than it is by theirs and then your mortgage is lower?
Mortgage lenders use the Home Report commissioned by the vendor for valuation.
Do you literally just have to guess? How can you put down an offer when you don't actually know how much the house is worth in the eyes of a bank, when you don't know how much you'll need to top up
The valuation is what is the Home Report. However you may have to offer more than the value to secure the house.
And why don't people just put what they want for the house in the actual price, with the home report in the description of the post, instead of this ridiculous process of, from what I can see, a guessing game
You do know the value so you don't have to guess that. What you do have to guess is how much to offer over the asking price. If you are the only bidder then you can usually get a steer from the estate agent on how much to offer. However if you find yourself in competitive bidding with a closing date then you have to put in a sealed bid with your best offer and hope its higher than everyone else.
The other way to go is to buy new build as they are all fixed price.