Thank you @Jessica Booker you have calmed my stress. I've honestly been up at night thinking about this stuff. Greatly appreciate your advice on this.
- It depends on what you mean by mid-size. Is this a UK-only firm? If so, the same applies as it would do for a regional firm.
- High demand fluctuates - what is high demand now could easily not be in 3-4 years. It isn't just about practice areas; it is also about sectors and knowledge in particular areas of law. All it takes is a major change in regulation or growth in industry/markets, and those could be the areas for higher demand for lawyers.
- Your TC firm will only find out if you are applying elsewhere if you tell them or put it in the public domain (e.g., mention it on social media/LinkedIn). Data protection alone means a firm cannot tell another firm about your application status.