Sir Mark Thatcher said his mother Baroness Thatcher would be "greatly honoured as well as humbled" by the Queen's presence at her funeral next week.
Green Party MP Caroline Lucas said she would prefer to spend time in Brighton than pay tribute to Baroness Thatcher.
The Labour MP for Rotherham Sarah Champion said Thatcherism "tried to destroy our town".
Members of Parliament travelling back to the UK from overseas to pay tribute to Baroness Thatcher can claim up to £3,750 in travel expenses, it was confirmed today.
MPs are able to claim for their journeys back following the recall of Parliament during the Easter recess, the Independent Parliamentary Standards Authority (Ipsa) says.
The man who provided police protection to Lady Thatcher, Bob Milton, said the biggest risk to the former Prime Minister's funeral is the "lone individual".
He said opportunists could use the day to "mark their hatred" for the former Conservative leader.
MPs and peers will today pay tribute to Baroness Thatcher after her death on Monday aged 87, after a stroke.
On the death of previous Prime Ministers, the Commons has marked the occasion with relatively brief adjournment debates - not a Government motion as tabled today.
When Edward Heath died in July 2005, MPs paid tribute for 63 minutes on an adjournment debate.
Sinn Fein leader Gerry Adams has criticised Lady Thatcher, saying "her Irish policy failed miserably":
Former Number 10 spin chief Alastair Campbell wrote on Twitter:
Former US President George Bush paid tribute to former Prime Minister Margaret Thatcher, saying she was an "inspirational leader" and a "great example of strength and character."