Far too early for getting the best price, cars are usually at their cheapest less than 3 months to travel. I am looking for 31st Oct this year prices are dropping each week just now, last week mine came down from £215 to £201, hope it drops a bit more yet.
Mid size? you mean standard? there is usually Intermediate, Standard, full size & Premium SUV.
I priced up Standard.
Your dates £391.85 less 8% Quidco = £360.50
Booking same car for next month £310.25 less 8% = £285.43
Prices are almost always better nearer your travel dates, or you need to at least book in a sale, I am waiting for another 25% of sale to appear like I got earlier this year, I picked up a full size SUV for 7 nts for £130.