Like you when I purchased my car last year I placed only a £99.00 holding deposit without seeing the car in the flesh. I confirmed that of I did not like the car I would be refunded my deposit. Did get confirmation of a refundable deposit if you were not happy with the car?
You will find that they will take you through the main features and request a test drive before signing any documents. During the test drive check that the steering is OK especially at 60mph - no wheeel wobble. Check the brakes and listen for any unusual sounds, knocks coming from the engine area and suspension.
Take a look under the bonnet and check the oil level, checks the tyre treads and a visual check of the condition of the bodywork for deep scratches, dents and knocks and for general good paintwork.
When stationary start up the car and do a couple of short blips on the accelerator and check the exhaust for blue/black smoke.
Check that all the interior controls work and all the windows work (go fully down and up)
In reality you are sort of doing a general MOT for your purchase.
If you find any defects that you are not happy with then point them out and request that they are rectified before you make any further commitments.
Hope the above helps you and if you buy it - enjoy it.😀
Regards
Olu