Hi everyone, and thanks so much for all your replies. All very much appreciated!

I'm sorry, it hadn't occurred to me to include any more details about my grandparents, Viktoria, but yes, you are correct - theirs was a wartime wedding. My grandfather was away in County Durham immediately beforehand, serving with the RASC, and came home on leave to get married. In fact, whilst I have always known the date of their wedding - 17th July 1940 - the penny only dropped last night that this was exactly one week into the officially recognised start of the Battle of Britain. They were married in Horam (not Horsham), East Sussex, so beneath the very skies were the dogfights were beginning to get underway. I also only learned last night that the first German bombs to fall on their district actually landed at midday on the very day they were married. It was very interesting to sit and reflect on how the timing of their wedding would have been determined by the war, and how the character of their wedding would also have been heavily affected by the war. I hadn't noticed that the car headlights in that photo had been fitted with blackout covers - what a fascinating snippet of information for me to include in my writing. Thank you, Youngtug!
Sourcing a newspaper is an excellent idea - thank you for the suggestion. I know that my grandmother's sister's wedding three months later somehow made the front page of the Sussex Express and County Herald newspaper, so I like my chances of finding something.
Thank you also, everyone, for the information about my Grandma's outfit. I've collated what everyone has said and, unless anyone has any other suggestions, I'll say in my writing that she "appears to have been wearing a cream-coloured dress coat, a light-coloured dress overlaid with white or cream floral-patterned lace and with a small bow at the neck, shoes with a bow across the arch (possibly but not certainly peep-toe) with gloves and an off-the-face felt hat in matching colour - possibly navy blue. She carried a horseshoe charm for good luck, likely made from silver cardboard, paper flowers and ribbon, and wore a corsage of white carnations and ferns in lieu of a bouquet." I will also make clear that some of these clothes were probably items that she already had in her wardrobe. Does that all sound about right? As a 45-year-old bloke with not even the foggiest idea about fashion, I honestly have no idea how to describe clothes! It feels nice to have been able to put together this description, though, as I agree she does look lovely. Thank you all for your help.
Finally, to pick up on one other of your comments, Viktoria, yes - they were very happy indeed. They were never hugely well off, and they had their ups, downs and health issues like anyone else, they were married for 59 years and both died in 1999 within two months of each other. I loved them both very much, and I'm now trying to write an account of their lives for my own children, who never knew them. Thank you all for helping me to achieve that ambition.