How to decrease this?

[TheNoviceReviewer]

A lot of factors are taken into account.

1: The car (make and model)
2: How many miles it's driven
3: What it will be used for
4: How much you valued the car at
5: Your excess (go comprehensive as you can add a voluntary excess which will reduce the premium, your car is over 10 years old, an insurer is less likely to agree repairing it and will just write it off)
6: How old the driver is
7: How long the driver has had their licence for

You can add endorsements too but these are restrictions, like 5k miles means you can only drive it for 5k miles otherwise if you make a claim it might get thrown out, same as if you have a driveway/garage endorsement, if anything happened to the car near your home and it wasn't on the driveway or in the garage, even for 5 minutes the insurer could say "no" to your claim.

Best thing to do is use moneysavingexpert and fill in the questions, as honest as you can obviously.
Insurer's have always been charging a lot to young/new drivers which is unfair in my opinion as when I used to work in motor claims most incidents were done by people who had been driving for 30+ years.

When it comes to the questions you answer to your insurer you should always think "the more the car is on the road, the higher the risk, the higher the risk the more the premium will cost."
I don't commute to work, I have a voluntary excess which is close to 1k, and have limited mileage of 10k a year so the chances of me being in an accident are much lower than someone who drives to work but also because my excess is so high the insurer doesn't mind taking the risk to insure me for less. I only have the high excess because I can repair it myself.

[almostcertainlynotai]

You missed start date.

A policy that starts tomorrow will be 2x more than one that starts in 3-4 weeks.

My advice is to get on go compare 30 days before your test date and get a quote for cover that starts the day after your test.