Summer Internship 2025

Hi, 
I am a little confused what to do next. 
I am a student from a non-target university in the UK seeking to break into sell-side.
I managed to secure an internship in Business Tax in Big4 this summer (The office specialises in HNW individuals and assisting deals). 
I am also currently preparing for my GMAT Focus. I have bought the resource packs and am sticking to a study plan. I am planning on pursuing a 2-year masters at a European target (Assuming my GMAT meets the cut). 

I have a few questions: 
1) Where should I be focusing my efforts for next summer for something with a medium-high probability of working, whilst bettering my situation? 
(For this, I think I should give a little context: Placement year in statistics, president of finance soc, intern at Big4, lots of extra-curriculars, first class degree etc).

2) Should I be putting any effort into securing something outside the UK? (I have only a UK passport). 

Thank you for taking the time to read this!