Navigating the Expansion Worker Visa Process for International Brands Launching in London

I am seeking advice regarding a UK Standard Visitor Visa application. I am already familiar with Schengen Visa procedures, but I have three specific questions regarding the UK visa process: Key Differences: What are the most critical administrative or procedural differences to consider when applying for a UK Standard Visitor Visa compared to a Schengen Visa? Prior Schengen Refusal Disclosure: Will UKVI (UK Visas and Immigration) be aware of a Schengen visa refusal received a few weeks prior to applying? Letter of Invitation Requirements: Unlike certain Schengen countries (such as France), does the UK require an officially certified/stamped original letter of invitation, or are digital copies accepted? Does including an invitation from a host in the UK typically expedite the processing time? I intend to travel to the UK in approximately six weeks to attend a sporting event. I plan to include a formal invitation letter from a UK resident to support my application, but I need to ensure this will not cause unexpected delays.

Quick question my partner and I have been together for 3 years but only married for 8 months. Will UKVI scrutinise this more heavily? We have plenty of evidence of our long-term relationship but I'm worried they'll fixate on the short marriage.