[Closed] Seeking advice on purchasing first road bike

I'm looking to purchase my first road bike which will be predominantly be used for commuting to and from work but also has the versatility to add a pannier rack and mud guards for the proposed challenge of completing Lands End to John O Groats later this year. I’m looking to spend in the region of £500 but wish my purchase to be a sound investment that will stand the test of time. Any help of guidance that one can offer would be hugely appreciated as these are my first tentative steps into the serious world of cycling.

Thank you

Jamie