Car loan? help

issyb

Looking for a bit of helpful advice, me and my husband are both looking to change our cars early next year. We own both cars and there is no finance on them. We are looking to take out a bank loan for approx £10,000 to cover both new cars. We are looking to trade in our cars against the new ones but this means we dont really know how much we will get specifically for each car therfore do not know how much we need to borrow for the bank loan? we did consider maybe taking car finance on each of the cars seperatly then taking a loan to pay off both for the full amount but not sure if this is too long winded and there is an easier way to do it?
would taking more out on the bank loan be a better idea then paying back straight away what you dont need? or would this incure early paying off costs?
Also how long from start to finish does a bank loan take to arrive into your account, sorry we have never had bank loans only got a mortgage so dont really understand the procedure. Total Newbees to it all haha!
Any ideas much appreciated x