I was also coming on to recommend Autoriesen for honest pricing although we've not hired a car abroad since before covid (mainly due to taking different types of holidays where we've mostly not needed a car) so don't know if anything has changed.
A lot of car hire places in Spain are crooks quite frankly who will draw you in with a cheap price but then give you the hard sell with a load of extra insurance and a fuel policy that has you paying for fuel you won't use. Do not use Goldcar under any circumstances. Buy your excess insurance in the UK as its much cheaper.
Moneysavingexpert.com has a good guide on the full ins and outs of this.
https://www.moneysavingexpert.com/travel/cheap-car-hire/
Make sure you have a credit card for the deposit. If you're one of those Mumsnetters who 'doesn't need to a credit card' hiring a car abroad is one of those times where its likely to be useful.
As for leaving the airport, have a look on Google maps and street view to see which lane you'll need to be in etc. From memory its well signposted and the roads are generally much better than the UK mostly good.
I can't drive a left hand drive car, I've tried a few times and can't get my head around it.
But I help DP by keeping an eye on his road positioning on my side of the car - apart from a small disaster the first time we hired a car abroad (he misjudged overtaking a bus at a bus stop and hit the back of it) he's been fine but likes to take a break from driving on holiday as he does it a lot for work, which is another reason why we haven't hired a car recently.