We would suggest allowing a minimum of 6 hours but yes you can. See this FAQ.
Top Tip: If Heathrow are landing on easterlies (wind from the east) You will most likely land on runway 09L. Those with a window seat on the left hand side (Not directly over the wing!) will be able to get a good view of the castle immediately below you on final approach.
Top Tip: If Heathrow are landing on easterlies (wind from the east) You will most likely land on runway 09L. Those with a window seat on the left hand side (Not directly over the wing!) will be able to get a good view of the castle immediately below you on final approach.