For example:
- if your 30 days starts today, November 26th, then you can arrive in the UK on any day between November 26th and December 26th.
- if your 30 days starts on Wednesday, November 28th, then you can arrive in the UK on any day between November 28th and December 28th (apologies, I miscounted in my post above - I'm so used to counting 28 days not 30 days)
- if your 30 days starts on Tuesday, January 1st, then you can arrive in the UK on any day between January 1st and January 31st
- if your 30 days starts on Tuesday, December 25th, then you can arrive in the UK on any day between December 25th and January 24th