A Westminster speaker isn't as oppressive as an American speaker, but they also are members of the governing party/coalition. Either way, the rules will be agreed upon by the House before business is done..
IIRC the Speaker is completely neutral, and doesn't have to be a member of the governing party. Betty Boothroyd was a labour MP and Speaker from 1992-2000 when he had a Conservative Government for 5 years of that.
The Speaker can end the debate, as seen when the condom of purple paint was thrown onto Tony Blair. However the government has large control of the Agenda, and set's the various motions. The Speaker is largely powerless